A bit of info in my thread over on the next page in the carb section: Radiator for Mk1 on carbs/ITB's I've opted for a Corsa B 1.2 8v rad, measures in at 530 x 285 x 25mm and will be sitting on the cross member and under the slam panel, to enable more room in front of the carbs.
I'll get some pics up tomorrow of mine. pics I have aren't very good but it sounds like the same rad.
There is a really short Vauxhall rad from an 82-93 1.2/1.4 Nova that measures 530 x 230 x 32mm which would allow for what you're after. Not sure how good/bad it would be for cooling though, with there not being as much of the core exposed to the front.
Not sure on a Mk1 rad but the Corrado rad I have is 440 x 320 x 44. I think a Mk1 GTI is similar, or is possibly wider?
1.2/1.4 8v Corsa B '94-'01 radiator: Corrado rad (rear), Corsa rad (front). Grille back on, may use a twin light grille without the spot lamps to aid cooling. Or, cut more of the grille lines out where they are blanked off on a single light centre section. Radiator not as far forward as most fit their's but should be ok? At least it's sorted my clearance with the big filters. (Rad isn't secured at the top yet but it can be moved in further)
Yeah it clears no problems. Doesn't make contact at all. I'll get the grill off in a few days and take some pics of the top, and the bottom where it mounts.