What year 454? Pretty sure they all fit, but newer ones (gen 6) wont have a mechanical fuel pump (pretty sure the new crate motors do), and i believe the headers mentioned are for oval port heads only (mark IV)

http://www.superchevy.com/how-to/4567-chevrolet-big-block-engine-generations/

I have hooker super comps on my 1978 454 in my 86 ss, motor has arp head bolts, and the drivers side leaked because the flanges just touch the head bolts a hair, double copper gaskets and now it only leaks a bit when cold, temporary fix (for almost a decade now so far, gees) until i decide to shave the header flange or the bolt tops, other than that, the headers work great, and with 3 inch pipes and hooker super comp mufflers, it sounds great and LOUD, more than one victim has told me they couldn't hear their own engine running until i pulled far enough away from them, but ya aint sneaking up on anybody

Good advice on the mounts, a/c box, springs, all i would add is to use polyurethane motor mounts, no flex

As for the turbo 350, they are pretty strong , but it's life expectancy will be determined by the power your motor puts out, but you can build it to handle the power