Not sure if you are going to keep the EFI or not but I did this swap and I went to a carb set up. I have a page on this on my web site that you can check out if you like.
Here are some details on the swap. It was a great project and if I can do it anyone can. Keep in mind that the ’94/’95 5.0 motors are not exactly the same as the ‘83/’93 motors so there are some differences.
The roller cam motors last forever, don't waste money rebuilding it, but do change the gaskets (intake, valve covers, rear main, timing cover, water pump, oil pan, etc and give the motor a good look over to be sure it is in good shape. One pleasant surprise will be the rear main seal; it’s a one-piece unit (ring) that you can install from the back of the engine without dropping the oil pan.
Early motors are balanced with a certain amount of weight at each end and they must match. My old ’73 302 was balanced using the 28 oz harmonic balancer and the 28 oz flex plate/flywheel. The 95 is balanced using a 50 oz harmonic balancer and a 50 oz flex plate/flywheel. With that in mind you will need a special balancer that will fit the front of the '95 motor with the 50oz weight. I believe the yoke (not sure what it is called) of the balancer is much longer on the ’95 motor and won’t fit right once you have the timing cover on etc so you need a ‘special’ balancer made for this application. I bought mine off EBay.
Be sure you use a flex plate (flywheel) that has the right oz. for your 95 engine and that will bolt up to your c4 torque converter. I called Summit and told them what I was doing and they had no problem telling me what I needed. I the flex plate from Summit.
Note that this refers to the size of the balance weights, not the actual weight of the part!
I use the term flex plate/flywheel because different guys call them different things. Technically speaking, automatics use flex plates and manual transmission cars use flywheels. If the 95 Mustang engine came out of a manual trans car you will need to change the part anyway if you are going to an C4 auto. Keep that manual trans flywheel if it comes with the engine, you can flip it on EBay for some bucks, maybe enough to pay for the proper automatic flex plate you need.
Also, if the 5.0 engine was from a manual trans car the crankshaft will have a pilot bearing in the back end of the crankshaft. Make sure to remove it because the nose of the torque converter needs to go into that hole.
The bell housing, exhaust manifolds/headers, intake, valve covers, timing cover, water pump, mechanical fuel pump, alt, fan, and motor mounts from the old motor all will bolt right up.
You will need thermactor plugs to plug up the smog holes in the heads. I think you need one for each head.
You need an eccentric gear to run the mechanical fuel pump or you will need to set up an electric pump. If you go EFI you need to do that any way.
The trick on the front of the motor if you go to v-belt is to make sure that all of your parts are from the same year. My timing cover/water pump/alt/pullie/belts are all from a '69 mustang 302 so everything fits and lines up.
I would used my old 302 distributor with a new gear installed. The HO motor has a steel roller camshaft and the old iron gear on the 302 distributor will wear out quickly. I bought the needed gear from Summit. You won't be able to use the 95 distributor unless you use the 95 computer. You will be able to use the wires, coil, etc. The '95 uses the smaller 'peanut' spark plugs that use the 5/8" spark plug socket, your old motor should have larger spark plugs that use the 13/16" socket.
Use your old valve covers, the new ones won't have a provision for the pcv valve, since the new motor located the valve in the back of the intake.
The HO motor has a double-hump oil pan, and if so you'll need to swap it for your front sump pan and switch the oil pump pickup tube as well. The oil pump pick-up and screen assembly should work from any 65-73 Mustang 289/302. In addition, the oil dip stick is in the block on the ’95 motor (between #6 and #7 cylinders). Make sure your headers clear it or close it up and use the dip stick that is in the old timing gear. To close it up I used a wooden dowel. Worked great and have not had any problems with it.
Add your intake/carb set up and you are golden. I assembled my motor, cleaned it up and did some paint. It looks pretty good. Drop it in and fire her up. I set my timing to about 14 degrees before top dead center.