Will a T56 bolt up to a 400 small block with no problems?

Depends on which version. There are several. There is one that is intended specifically for third gens. It even has a mechanical speedometer. The ratios in it are 2.97/1.94/1.35/1.00/0.84/0.62

Bellhousings bolt to blocks, not transmissions.. There are many T56/400sbc combos, you have to be more specific of what you're looking to do.

It will work, but it requires a special aftermarket flywheel to do it (assuming you are using an LT1 setup, which is the easiest route for a SBC). The flywheel is a special one because it has to be like the LT1 flywheel, but 'unbalanced' for a 400sbc, and have the 2pc rear seal bolt pattern.

centerforce sells the flywheel for 400's that u need to make it work

I have the LT1 T56 behind my 400 block. You need the flywheel from centerforce as stated above. But then just buy a clutch for a LT1 motor.

im thinkin bout doing a t56 setup i dont know which one to use though, they make an adapter plate for th ls1's that allow you to use everything that u already have so u kinda save money but then again the lt1 is externally balanced but u would have to change everything. which route is better for me in ur guys opinon? I got a 383 with 4:10's and the block is externally balanced