Bring your Turbo Optima and 112b along some time and I'll take a look at at. I'm sure its still usable and I'd rather like one again so might buy it off you! As for transferable - well I don't think the 112b can handle modern motors, (IIRC it struggled with 19t's back in the day) and your batterys are never going to cut it, but I guess if your radio gear is OK thats still usable.
4wd is the most common class at Bury (though oddly 2wd is more popular down the round at Southport!). The
Associated B44 is a good place to start - About £235 and race ready from the box.
A brushless motor system starts around £100, this
Exceed system is seriously nippy, probably a bit much to start with.
The B44 takes saddle pack batteries, and you'll be wanting modern Lipos. These
Intellects from Demon are a little large but will last you a whole days racing with a little topping up. They'll need a suitable Lipo compatible charger -
this one is mains and 12V so work indoors and out.
Of course you could save a lot of money up front and get one of these : A
Kyosho Lazer Brushless which sorts out the chassis, motor, esc and radio. Its needs a lot of upgrades to reach full race spec, but is good enough to start with. Likewise the brushless system is basic but will do for now. And since the car takes stick lipos not saddles you can get this
Trakpower pack. And you could save on the charger with one of
these.
Hope that helps!