While shoving the biggest piston in it (2.815) without resleeving the block. also jam as much crankshaft stroke in it too. .175-.200
no matter what track size, start with more displacement. then add the appropriate cam, timing, ect, for the track application. Stock carb must be used ? A built carb to run on Methanol with a venturi bore of .650-.670 should put you close to matching the engine. a thousand ways to build these things. lol
Good Luck....