saw this over on YB from 2014:

"Re: MOPAR B1 COMBOS

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we ran a b1 original headed 540 in my leaf spring 275 dart at 3300lb and best was 5.07@140mph

I don't know of anyone else that has sprayed more on a b1 original than we did, 48 jet, reliable engine but camshaft very tricky, really didn't respond much above a 40 jet"