Hi DapperDan, welcome to the forum.
It looks like you're at the stage I was just over three years ago when I stumbled upon the Sammio Spyder whilst trying to find an unstarted GP Spyder (Porsche 718 RSK) kit on ebay. It leapt out at me as a stunning looking homage to the fifties racing car that I could actually afford to build, and, like you feel now, I just had to have one.
Two years later and I was driving this home from the MOT centre with the world's biggest smile on my face -
To answer some of your questions, I believe the move towards Spitfire donors is solely due to numbers available - there are just less Heralds and Vitesses left so prices are rapidly rising - rather than anything to do with the looks or handling.
With the easily available adaptors and spinners -
http://www.ebay.co.uk/itm/SAMMIO-SPY...item51c2caec6d http://www.ebay.co.uk/itm/SET-OF-4-M...item3a9893e87b - you can fit any 42mm splined wheels from the MG or TR5/6 range.
MGB 4.5x14's are cheap, plentiful, look the part and (with a bit of preparatory bulkhead bashing) fit perfectly with the right tyres, typically 175/80/14's.
15" wires in various widths from the MGA/MGC or Triumph TR5 or TR6 are harder to come by, tend to be more expensive and restrict your choice of tyre rather more if they're going to fit without serious fouling issues.
As a guide, 175/80/14 tyres
just fit, so anything with a larger diameter is going to need more modification to the bulkhead and possibly the steering rack. You can use this calculator to compare different tyre sizes -
http://www.kouki.co.uk/utilities/vis...ize-calculator
Interestingly, for a more modern look on a budget, MGF wheels have the same PCD as Triumph hubs so bolt straight on. I understand you need spacers on the back and you'd need to pick your tyres carefully, but the MGF 'minilite' style wheels don't look out of place on these cars and are really cheap -
http://www.ebay.co.uk/itm/MGF-MG-TF-...item51c16da0d4
And finally, don't worry about the lack of symmetry in the body shells, nobody has ever pointed out that as an issue on my car as they're all too busy admiring and complimenting it.
If you go to Goodwood Revival and take a good look at the multi-million pound 50's racers there, you'll notice that they too tend to have little idiosyncracies in their designs that were forced by constant development, so a really 'true' body would actually look less authentic.
After all, these three Sammio 'originals' don't look too shabby now, do they.
