You'll need an adapter to mate the transmission to the block, and it will be necessary to convert to an open driveline setup. Basically, you'll be changing the entire driveline system from the engine back. When you go to V-8 power, a lot of the previous modifications can be reused, so it won't be a totally wasted effort, but if I were given the choice, I'd to the whole swap now, rather than make two bites at it.
Jerry
