This has been written about before but thought I would record my finding for others to compare, details as follows:-
1957 Magnette ZB
Standard wheels, tyres (radial), rear axle ratio (4.55 :1)
Ford 109 gearbox Hi gear conversion.
MGB 1800cc Gold Seal 18V engine (1972 - 74) Hi comp (8.75 : 1), good oil pressure, good compression, thought to be little warn.
Magnette inlet manifold, original 1.5" carbs, 90 thou jets, original air filter housing fitted K&N element.
Tried MB jets (as fitted to original early MBG with similar carbs) on rolling road but too weak at higher revs, fitted AO jets which gave expected 90 bhp and started to go weak above 4500 rpm, decided to leave them as I don't tend to use high revs!
St St exhaust system (Derrington inspired) bought thru' club.
Car runs very well, is nice and responsive and a pleasure to drive.
I hope this info assists some members who may have similar setups.