When it comes to early Chrysler hemis, especially the truck stuff, a lot of their ID codes aren't in any database. Your engine could be a Canadian version or a replacement block, its impossible to know for sure, so don't be all that concerned about that part of it.
Now, the thing to remember is that the general specs for any 354 will work for yours. That said, if your engine came from a heavy truck the heads will have a taller water crossover that will not seal against a stock automotive or aftermarket intake manifold. The solution is to pick up another set of heads or you can have the top of the water passage welded to bring down the top so it will seal. You'll wan to replace the normal internals, pistons, valves, cam, lifters, push rods etc. If your engine has adjustable rockers I'd keep them. They're hard to find and you can use a solid lifter cam with those. If you don't want to use a solid cam then you can sell them and probably make enough to buy a reconditioned set of non adjustable rockers, new cam, lifters, and adjustable push rods. You may also want to use an aftermarket front cover and convert to a BBC water pump. Hotheads has those and just about any other parts you'll need.
Good luck with your build.
"Running a small block Chevy is like having a girlfriend who wears a push-up bra. The numbers look great, but once you get under the hood, there's not as much there as you thought." - Anonymous