Thanks for your interest, guys.
Great inspirational youtube clips, Paul - the first one is very much the look I'm going for with the front cooling vents and '550' feel inside and out.
Biggles, I did start by swapping over the suspension turrets which moves the engine mounts back too far, pushing the gearbox way back into the cockpit and leaving no clearance for the exhaust system. I would've needed to use a 4 into 1, Herald/early Spit/MG Midget manifold and narrow bore, modified down-pipe to clear the chassis rails, and I'd already got a 4-2-1-2 big-bore stainless system that I wanted to use.
As I only needed to move the engine back by two inches to get the front carburettor dash-pot under the bonnet, and I already had an overdrive prop on the shelf, which is 3" shorter than the Mk I-II-III prop that fitted my MkIII spec engine and gearbox, it seemed sensible to just move it back by 3"
That's put the engine fully within the wheelbase (so it's now technically mid-engined), given plenty of clearance for the front carburettor, (just) enough clearance for the exhaust system and left more space ahead of the engine to install the radiator and ducting to get the air from the MGF cooling vents through the rad without wasting any.
Anyway, I'll be getting on with this project again shortly so will post more pics when there's visible progress