I have recently recieved two modified engines supposedly a 351m and a 400m. the price was right and i couldnt pass them up, upon arriving home i had the depressing relization that i hadnt a vehicle to drop either engine in. after doing some research i also found that this is a very neglected engine with imense potential. ive always liked standing out so originally i was thinking a 427 stroker with the 400m with a set of cj heads. but then i thought maybe destroke the 351 and run a high rpm engine. long story short i need to know what the safe piston speed is for the 70s and I need to know the crankshaft bearing thicknesses and journal spacing in a 351W (THIS IS NOT A MISPRINT) the crankshaft i found uses a 3.00 crank bearing and a 4.25 stroke built for an aftermarket windser block for a 454 kit. i cant find a 351w without having to buy it. all help is appreciated, suggestions also appreciatedbut keep in mind im using the modified becuase noone else does, im not lookin to just throw 331 stroker from summit in it. o ya, i was thinkin of putting these engines in a crown vic or station wagon, maybe a f100 if i come across one cheap.

 

check out the 351C-351m-400 forum on this website-lots of info telling you what you can get away with. Nothjing so specific as piston speeds etc, but I think I know why you are asking.
T meyer has a 434 kit at a very reasonable price so dont go off too hard on your own.
There are bigger kits out there for the 400, but all comes down to cash.
I wouldnt waste your money on destroking a 351m-They did a similiar motor here in aussie by destroking the 351C. It became the 302c aussie with the closed chamber 2V heads that are so prized in the 351m-400 community.
Now thats a good little engine with a lot of potential even if it is the same block as the 351C, but going with that logic, smalling down the 351m capacity wise is still feasible, but remember you are starting with a slightly larger heavier wider block than a 351c so maybe not so user friendly.
BUT, IMHO, little engines, no matter the HP, are for smaller cars. The bigger the vehicle, the bigger the engine.
Mass usually needs torque and down low to make things move. Cranky smaller engines can have a lot of HP and a lot of torque also, but the it is usually up the rev limit, so not so useful. A nastly little 302C in a smaller mustang would be a good thing!!