Hi Steve,
Sorry, I hadn't realised that you were ill. I know you frequent the non-airgun section but don't pop into here very often, so please accept my apologies and all the very best to you.
Re spring guide fit, I like them to be a tight push fit. So, a firm push with the palm of your hand and a fair bit of resistance, but not requiring hammering in.
Metal piston sleeve is fine; leave as is.
I'd be going for a top hat.
De-burring - just make sure the cocking slot is smooth and ensure the inner surfaces on the various cut outs on the inside of the cylinder show no sharp edges which may snag the piston seal when re-inserting.
If you can make your own guide and top hat, fantastic.
If not, a V-Mach kit (either full kit or just spring and guides) or a TBT kit will be fine and have those guides custom made to that particular spring. I also really like the SFS springs for the '95, and they're made to fit the standard nylon guide, but you'll need a top hat.
A sparing re-lube on reassembly and all will be good.
Whilst it's apart, double check the piston and breech seals and the barrel shims and replace if required.
All the very best on your little rebuild and best wishes for the future and hope the treatment goes well.