I dunno if you have them in Canada but in the US, we have some used
marine "junk yards" of sorts ("shipwreck marine in Sacramento, Calif and
another one's near Stockton).

I'd opt for finding a block that is used somewhere.

As for weight, it wouldn't be that heavy but instead awkward to lift out
with 2-3 men. I'd suggest buying a "comealong" winch (Northern Tool Supply)
and hoist it out from a rafter or a strong tree (or build a temporary A-Frame
out of lumber). you could drive the boat to the proper location, hoist it
out and drop it in the bed of a pickup truck. Putting a different block in
it would cause you to have to relocate engine mounts and you may have
an issue with an outdrive that can't handle the additional torque.

b.