Many people say the originals (with rebuildable screwed together body) are excellent, while some/most aftermarket replacements (one piece, non rebuildable) are junk. I know that my 37 year old fuel pump is still a-going just fine. Only a cleanout has been performed: disassemble, clean and resassemble.

You can still find rebuild kits from time to time, just be aware there are two or three types of A-series kit. The only thing that wears/needs changing usually is the diaphragm so maybe any kit will do.