this is probably the wrong place to ask this but i'll try
i have a 413 sbc (400 0.060 over), 4-bolt main,externally balanced, 1971 block
will lt1 or ls1 top end work with this motor, (manifold,fuel injection system,cam,heads,etc)
will any of this fit?

i also want to use a t-56 as my tranny, will it bolt up to my motor?
will i have to make any major fabs?

the reason why i just wont go out and buy an ls1 or lt1 is because i built the bottom end (eagle rods,pistons, crank,etc), thinking i was gonna build a car, but that went down hill, and i have a lot already into this motor, so i wanna use the ls1 or lt1 set up, i like the set up

thanks guys

 

LS1 won't work at all, totally different motor design. LT1 intake will work with modifications to the intake for the distributor to work, you will have to run the TPI distributor, wiring and ECM from an TPI car for the fuel injection. Heads for the LT1 will work with major modifications since the LT1 is reverse flow cooling and doesn't have the provisions for water to go through the intake like a standard SBC. You will have to drill the front of the heads and tap them for water fittings back out to the water pump. You can do a search on LT1 head modification and should be able to find the info for this. LT1 cams won't work since they are roller and your block is for flat tappet. You can do a roller retro kit for the roller cams to work.

 

You can use the LT1 T56 behind a 400. You're going to need a special flywheel.

Personally, I would go with an aftermarket stand-alone EFI set-up before I'd try to modify an LT1 induction to work on a Gen I. Well, what I personally did is go out and buy an LS1/T56. When I added up the cost of improving what I had and converting to T56, this came out as the most reasonable approach.