No, your machinist will bend you over for doing that.
They want new parts to work with. Unless you had 10 rear caps to test fit and one was close.
You will pay 3x to 4x what you think you are saving on the new rear cap.
First, go with E85 like i've been hounding you for years. it will love the 200' temp, the elec pump is not street and not needed.
Have Tony make you a duel fan shroud with the spal or your fans. Didn't i show you the one he made me?
I also have my new duel intreped fan you can have
You can find a stock cross over.
If the original lifters are out of order they are junk now. toss them
Unless someone can vouch for new flat lifters, you are stuck going roller.
The benefit of the stock crank is cost. You don't need a crank at your level. You can find a STD crank fairly cheap...
Use the stock exh manifolds, have them welded if needed.
Use your original lifters with the stock cam in the same order they were in, if not go roller. If roller you need to cut the exh guides. Springs ect.
Is the crank internal balance? You will need a TA balancer and flex plate
AES should be...
I never use the supplied rubber ends.
Drop the intake on the heads, shim using valve spring shims to make sure the ports line up.
Never use 1200's unless you have fully ported GN1s, all other applications I use the factory tin valley gasket.
RTV the ends in lieu of the rubber ends.