Well what bore size is marked on the block (all B?) first you have to strip the block,
check crank journals you can run early crank and there is nothing wrong with strength but the oil ports etc aren't machined out very well they got better through the years.
Throw away the rods and invest in some forged h beams with new arp bolts or find some v7 sti rods
I've got a set of hf pistons from v5 sti block that are good to reuse you can buy them from me(pm if interested) if you want/going this way. If your building a engine something over 20psi then you might want to go full forged. factory pistons are still a weak point but obviously cheaper option.
You real need to measure everything, the bores especially, remember they need de-glazing and machine shop is able to do this best(ie won't tapper the bores.. So thats when you should start thinking about new .50 oversized pistons new rings and bores machined to suit but obviously the safer option is always the most costly but most practical
If its just surface rust on the cam lobes clean it up with metal polish if its pitted use some engine oil and wet and dry 320g sandpaper.