Comparing the original Mini to a 128 Fiat I would guess the Mini handles better out of the box, ( I never drove the Mini, but was a passenger many times) The 128 will respond well to lowering, sway bars, etc. The early ones like the 73 you are considering may have been lower than my 76, 78, and 79s. It seems that they raised the height when they added the US spec heavy bumpers. The "73 probably has a 1100 motor which is fairly anemic, but a 1300 or 1500 motor without smog, a header and exhaust, a tweaked or dual carbs will make it a fun driver. Probably on par with a 70s BMW 2002. As far as collectability, the variant models: 3p, Sl coupe, original 1300 Rally, and to a lesser extent the wagon, probably command a higher resale. I think the Sl was desired for racing due to the improved aerodynamics. I almost bought a turbo, lowered, Flared, Sl coupe with a roll cage and a fuel cell. But smog rules and the fluttery feel of the valves under boost in the primitive turbo set up gave me a distinct impression the motor as not to be long on this earth. Courtney Waters or Jeff Stich could probably chime in for some more recent impressions.