Maybe find a donor truck?

That is what I did way back when. I found a '77 400 truck that had been wrecked. Never did understand what exactly happened. Truck still ran and drove surprisingly good despite the damage to the bumper and grill. The weird thing was on the side of the impact, the side of the block was broke off too. When I pulled the mount out, it still had a chunk of block attached to it. You could see the cylinder wall...... But it ran beautifully.

I stripped the truck of everything I needed and then some, and sold hat was left to a co-worker that made a trailer out of the back half . Probably the only time I came out ahead on parts.

Before I found this wrecked one for parts, I can't tell you how many 440 trucks I found with a 2bbl on it............. (they weren't 440's)