If you want to upgrade an old RF 'cocker here's your options:
you can get the new E2 or Race frame, or a Centerflag uprising. An E1 won't work because the feed port is in the way of where the eye would go.
Barrels
Valves
Hammers
all front block parts (ram, three ways, regs), but not all front blocks. The old style 'cockers used a smaller front block screw, you'd have to have your body redrilled and tapped in order to use a new (2000+) front block
ASA's
regs
back blocks (old style blocks were longer, and subsequently require a longer bolt, but you can put a 2000+ back block, and subsequently any 2000+ bolt, onto any autococker)
Bolts - covered above
Pump arms
Actuating rods/collars
Cocking rods
Grip frames
Velocity adjusters (old cockers used a smaller main spring, but you can put in a velocity adjuster and use the wider, new style spring)
Springs - covered above, all other springs are universal
Screws
Pretty sure that's about it. You could spend hundreds of dollars upgrading or building an autococker. Once you start "upgrading" an old 'cocker like that, you really just wind up rebuilding it. You'll probably end up even getting a new body in the end and transfering all the cool new parts you just bought. If you like building stuff, it's kinda fun, but it'll cost ya just as much as a new one would.