Peterg,
I suggest you check the sizes of the current jetting with jet drills as over 60 plus years owners often drill the jets larger.
The only accurate way to decide on jets required is to connect a gas analyser to the exhaust . I have found a mobile gas analyser on the road is better than
a rolling road dyno. When you know if it is running lean or rich at a particular rev range a decision to change jets can be made.
We might normally think that fitting higher compression pistons would require larger jets . This could be the case if the engine had previously been rejetted & adjusted/tuned accurately . But most Bristols with standard jetting run too rich , often a combination of high float level , worn jets over time and use of higher octane fuel than in the 50's.
Probably best to get an expert with a gas analyser and selection of solex jets to tune it and rejet as necessary. It could be cheap insurance for the money spend on a rebuilt engine.
Geoff
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