Mike, the reccomendation of an M20 is a bit of a headscratcher since the original quesiton Jay asked was about a 5 speed. Unless my math fails me, the M20 falls a gear short. To some people, overdrive is critical. To others, its not. I'm assuming since he is asking about 5 speeds, then it is important to Jay.
I said keep it and use a milder rear gear. Let me clarify my point.
Many people with 5 speeds in mind, are looking to keep the highway revs down. The nice part about having 5 gears is you typically get a nice deep 1st gear performance, coupled with a nice highway combination. Best of both worlds.
Now, if one does not care about performance enough to put a trans that will hold up to the occasional abuse of a high torque 455, then it should not be as much a concern to keep the 4 speed and run a gear like a 2.56, 2.73, or 3.08 either. Granted the off the line performance would be less, but what does that matter if you were going to have to baby it anyway?
The M-20 has a decently 1st gear to begin with, so even with a highway gear, when coupled with a 455 it's still going to get off the line pretty good.
Since only Jay is sure what is important to Jay, then it's nice to let him know there are other options. And others use these threads for their decisions as well. So this is food for thought for the OP and others. It all depends on goals and budget.
Yes, his question was regarding 5 speeds, but that doesn't necessarily mean it's because he wants to shift 5 times to get onto the highway.
