No need for drama. :-) Itís can be a bit of a challenge if the person assembling is different than the person machining. Thatís why you should be checking everything. The first time is fun. The second? Not so much.
Inherently parts is parts. If the machine shop did his job, the valve seats in the heads have been modified to fit the Chevy valve sizes. No biggie. As mentioned, no real reason to do it these days, as there are a lot of other options, but whatever as the kids say. Chalk it up to old-school thinking.
Also, as mentioned, youíll need to pay close attention to the rocker arm geometry and push rod length during the mock up part of the build. But you should be doing that anyway.
If the shop has done this in the past, they should give you an idea of which pushrods youíll need. But, you still have to check.
Get back to work! :-)
1969 Mach-1 Mustang
460 / C6 / 9"
Back in Dixie DSO 22 (Charlotte)