Lowering by raising leaf spring mounts

[76C10Stepside]

Have some questions re lowering and replacing the bed wood for y'all...

LOWERING (cheap but safe):

The rear leaf spring mounting brackets can be moved up on the frame rails by a good 2 inches in front, and an inch in back (more if I can relocate the cross piece that's right above it).
Q: Anybody out there done this before? Anything I should know about before starting?

The ride in back has gotten progressively stiffer the last couple years. It has air shocks in back with a single schrader valve. I've never added air or let any out. I tried letting air out today, but nothing happened, so I guess these shocks are probably toast. Will take them off and test them before tossing.
Q: Suggestions for affordable but good shocks? I don't do a lot of hauling, mostly engines and stuff.

REPLACING WOOD BED:

The original wood bed is totally rotten. Fell through a couple times now.
I don't have covered parking for this truck, so don't want to use wood.
I think the charcoal colored "Trex" style "engineered wood" would look great.
I'll refinish all the metal with black bed liner.
Q: Anybody out there found a suitable product that has the right dimensions and is strong enough to replace the bed wood? I've talked to sales people at Home Depot, etc., and got nowhere. One time I went there I found some nice stuff with a dull finish (like it was sandblasted). Next time, it had been replaced by stuff that as a fake woodgrain embossed into it and is shiny, didn't like that.

Thanks!