I am installing a 200 4r in my 65 442, stock engine 400, new TC how do I know if the shafts on the transmission are seated in the TC far enough or correctly? Is there any special trick or does it need to be seated correctly or it won't be close enough to bolt on?

 

if it is not in all the way it will most likely hit the flexplate before the tranny buts up to the block. you should not be able to get your fingers behind the convertor. if its in as far as it can go into the bellhousing the shafts on the tranny will be in.
just make sure when your bolting the tranny up make sure the convertor spins free before you snug it up on the dowels or it can break a bunch of stuff. if this happens you will know that the convertor is not in all the way! hope this helps

 

If you pick up on the convertor so it's square with the shaft, and turn it one-way, while lightly pushing in, you'll feel it 'catch' and it'll go in almost an inch.
Then it's seated.
After the trans is bolted up you should have about 1/2 inch of play to the flexplate.