No.
Like I posted, the 351m and 400 both use the 385 series(429/460) bell housing pattern. As was also posted, a crank and a set of pistons will convert a 351m into a 400 and I'd recommend it, if you're going to add all the weight, you might as well add the cubes, too.
>>>One thing to keep in mind: mid 70's 351m's and 400's had problems with the block cracking in the lifter valley and allowing coolant to ooze into the oil. If the sides of the valley are flat, it's the crack prone block, the revised block has a wavy surface on the sides of the valley.
Roller cam 351w's shouldn't be rare, we sold a pile of them in F series and Broncos in 95 and 96 and quite a few in 97 F 250's and 350's.
Your bio says manual transmission, if that means creeper gear 4 speed, it should live behind about any engine, you'll just need to find a different bell housing. Actually, if you have a 3 on the tree, it would probably hold up, too. Late 60's Pontiac performance cars used a Ford 3.03 3 speed behind their 400 if and automatic or a 4 speed wasn't ordered because GM didn't have a 3 speed that could handle 400ci.