Chris well i would go one of 2 ways. stick with eh MFI but return it to standard fueling i.e. no profile block and fit a standard but locked dizzy. Then use the omex box mentioned for mappable ignition and and MF2 (or similiar) for suppling the extra fuel required. this shoudl yield good cruising economy, well dialed in ignition and fuel requirements and would be cheap(er) and easy(ish) to fit.

the second would be go full on fully mapable, i would be looking at DTA tbh rather than MBE(my reasons being TVR based). This obviously would be the best all round solution giving maxium performace, economy and scalability(traction control/FTGC etc) but there the cost and the requirements for a complete map and also you would need to source the majority of the 2.8 EFI parts, not an easy task i tell ya.

you pays your money you takes your choice. i just don't feel the whole saab reg thing and tweeking the fuel dizzy is the way to be going. also scoob says there aboost limitation of the dizzy module 12psi IIRC