PLEASE NO! Do not buy anything from ATK/Spartan/Surefire engines
While I have no experience with ATK crate engines, I did put one of their cylinder heads in my F150 after it dropped a valve. What a horrible experience!
To make a very very long story short, the first complete cylinder head I received had the wrong cam shaft. It was about 1/2" too long, which was just small enough to not notice when buttoning everything up. Ended up destroying a 400 dollar cam phaser, and luckily nothing else.
ATK had ZERO understanding of how this happened, zero traceability from their build, and were not willing to help at all. Luckily I bought through Autozone, so they took the return.
Second head had a bunch of exhaust manifold studs broken off in the head.
Third try, they finally got it right. 1 month without my daily driver, one destroyed cam phaser, and the delight of doing the entire job twice.
ATK was entirely unwilling to help, offer any assistance, explain why they were having issues, or even pick up the phone half the time.
DO NOT BUY ANYTHING MADE BY ATK!