If you find that wasn`t the short that caused your blown link then I would check the ignition switch connector at the the base of the steering column. Many times they melt and short out and cause problems like yours. I would replace with a fuse link if possible. Also make sure you use the...
Honestly many of the newer made standard replacement pumps are crap. Most made in china india etc. I have not had good luck with them. The summit pump is pricey but much more reliable. I have used the holley pumps with good luck also.
IMO You basically really need the later trunk floor to do it. Just later straps and brackets won`t cut it since the 76 floor has a completely different shape. You could locate a used trunk floor and drill out the spot welds and replace the whole trunk area. Anything other than that may look...
call Leon at Silke's Auto Parts Inc JACKSONVILLE, FL 32217 they show 2 in stock. 4058129 there is also a superseded part number that I forget at this moment.
They are hard to find new on a 2dr. I never tried to find one for a 4dr. Probably getting obsolete also Ask for the part number so you can do your own search Looks like it may be DW859T. Classic Industires shows them online. Not sure if the really have one