Check your flex plate maybe that's what is making a knocking noise. They do today when there cracked.a lifter sounds more like a ticking sound. Flex plate sounds just like a rod knocking.
Damon said:Truck TBI engines are flat tappet. Car TBI engines use roller cams. The truck block MIGHT be a roller cam block (it's kind of a crap shoot- some were, some weren't), but even if it is a roller cam block it will have a flat tappet cam and lifters in it.
TBI heads are the weirdo 87-up bolt pattern. The center two intake bolts are "stood up" at a steeper angle than earlier heads. You can modify an earlier intake to fit, but I wouldn't bother. The 305 heads off your old engine would work just as well as the factory TBI heads.
If you can build up that 400 in a reasonable timeframe I agree taking a pass on that 350 TBI engine would probably be a good idea. If you just need something to throw in it real quick to get it running, then pick it up, swap your 305 heads and intake onto it and drop it in.