Looking for some advice on rear brakes, rears currently drum. I am fitting bolt on shafts and hubs.
I have a pair of alloy calipers alfa 145 32mm bore that would need an adapter or new mount to fit, is 32mm to small ,or
shall i save the hassle and fit the sierra ones i have. Thanks in advance as i am off to work now and cant reply.

Sierra ones are 42mm bore -- thats a lot more hydraulic area -- nearly twice the brakig force.

An alfa 145 must be nearly twice the weight of a 7 so the rear brakes will be fine or even too good.

Rear drums provide adequate braking for a 7 (in the link below they are actually too good!), so there aren't really any disk/caliper's that are too small.

Sierra rear calipers will need some kind of brake reduction valve to avoid locking up before the fronts, but there are restrictions on what kinds you can use for IVA. See:
http://www.locostbuilders.co.uk/viewthread.php?tid=122978

keep the drums there is a guide on the sierra owners club with bolt on shafts. rear callipers are a pita