F877 to F877A Brain transplant w/HEX

[boroko]

Hi all,
I have an unusual problem that one of you may have run into.
I have a couple of controllers on the bench for repair. Same board and configuration but one uses a 16F877 and the other used a 16C74A.
The one with the '74A took a hit that blew it up.
The rest of the board is the same and I can get the HEX out of the 877, but I only have 877A's here.
I don't believe that I can load the '877 HEX file into the "A" and use it. It seems logical that the HEX could be disassembled and recompiled for the "A", but I haven't ever tried.
I imagine I'm likely to run into a flood of people screaming that I'm trying to rip someone off, but I'm not. I just want to duplicate a burnt chip (in this case , with a newer version) and use it back in it's original device.

I don't know if I can even get plain 877's any more.

Any thoughts?

UPDATE: Next Day Air'd a couple of plain 'ol 877's from Digikey. We'll see if I can transfer and run the code on a new chip without any problems.

Thanks
Bo