I'm not as familiar with Solex carburetors as I am with Webers but I would venture a guess that 40mmm Solexs would be comprable to Weber 40 IDF's. I would suggest a build of 1776cc or no bigger than 1835cc for optimum carburetor performance. A set of good d/p heads, maybe an Engle 110 or 120 cam, with a good set of rockers, and maybe a Pertronix module in your distributor. The case and heads would need machining to accomodate the bigger pistons and jugs but the bore for 90.5mm and 92mm jugs are the same size. Like I said, research your options first, build second.