First post, hopefully I'm in the right forum

A compression test on my '89 F MFI XR3i Cabriolet revealed one piston has significantly less compression than the others, so now would be a good time for an upgrade.

I want to keep the car reasonably standard (no turbo or ZVH) but if the head is going to have to come apart is it worth spending a bit more and going for a fast road cam or a polished and ported cylinder head?

A rebuild (with a bit more power) was always on my list and I've got about £500 saved up, so my question is what would you do?