BBB into 1970 C20 Chevy truck. Need help!!

In some years Chevy used Buick Nailheads in there heavier trucks and called them Loadmaster. I was wondering what would have happened in the late 60's / early 70's if they kept up that trend. Looking to put a 430 or 455 into my Two-wheel drive C20 Chevy truck. And throw on some loadmaster emblems.
The truck is a flatbed. and will be used as a shop truck/ trailer hauler. for loads up to around 8000lb.
It has a Sm465 trans now. I have a Buick bellhousing from a 300. May have to get the center hole enlarged. and not sure if the small block bellhousings will accept an 11in clutch.
I may look at using a NV4500 5 speed instead. as the truck has 4:56 rear gear. an OD gear would be nice. Gear venders would be another choice.
Running 30in tall tires.
I am ok with routing fuel lines and such, and in the future after i have everything running good will be running it on Propane.
Do you guys think the 300 bellhousing will work??
also will the engine mounts bolt up to the factory chevy frame mounts??
Need some solid advice Please.
Thanks in advance.

 

There are 2 chevy truck I know of in my area that have bbb in them. 1 is an older tow truck.....he said the torque is why he had it put in, the other is just a driver.

I can answer you question directly, but it must not be too hard to do if these guys did it as neither has major skill levels to do alot of custom work if u know what I mean

 

Ben99gtp.
Needing to know what engine and frame mounts work together for this combo
and if the 300 bellhousings will work with the SM465 trans or a Nv4500
also, if the 300 Bellhousing will accept an 11in clutch.
If there are pics of this conversion. I would love to see as many as anyone can post. Thanks.