Mostly depends on what you want from it, and budget.
A rebore if needed taken to +90 with V6 colonge pistons gives a usefull increase for no extra cost over a std rebore, as 2086cc results, lightening the fylwheel is next in turns of bhp/£, but also if you have the whole engine lightened/balanced it will just rev so much better, then there's different head, ie ported, start with an injection head as ports are better std, get 3 angle seats cut.
Like I say budget is the unknown, but the above with a nice cam and carb(or injection) will give the most bhp/£.
I always ran my pinto's with and extra 1 thouh bore clearance, made it so much freer, my last was a 2.1 with a 32/36 with a high torque cam(was automatic) exhaust etc, modded A4LD gearbox with adjustable valve chest and pumps, would obliterate my mates 2L pinto manual injection sierra, as would my 1700cc mk2 escort auto, again modded box with stall convertor based on 1300 vanes, again on a 32/36.
Sierra later went to 40DFI, god that woke it up, as did the fuel consumption, 40DFI is rare and was performance upgrade for old V6 3L essex engine.
tabetha