Jet it down, man! Stock jets are about 61, way too rich for a restricted exhast. They are fit for about 135 hp or so, maybee more with the right exhast.
Since the stock Holley has a rich fuel jetting, and could stand being taken down to 54 or 56 thou main jets and still be rich. Use the same squirter jets, and keep the power valve down to 6.5. Stock power valve was 8.5 or 10.5. Some of the smaller jets are harder to get. Close limit 512 primary jets from the 390 cfm would be the leanest I'd look at. The stock oxygenated fuel gives a leaner fuel air ratio than what Holley designed the 350 cfm carb for. It is afterall, a carb designed for a 129 to 164 hp 302 or 351M, and you'd be lucky to be getting 95 hp as it is.
The size of the 350 Holley is quite large, but it atomises fuel really well if you drop jets down to the smaller sizes.
I recall 125 hp Pinto engines running 56 jets, 2.0 power valves, and a set of power valve channel restrictons.
Another thing. The vacuum advance needs to be seeing the same vacuum signal as it was with the 1-bbl. Use a timing light. Mark TDC by dropping plug 1, and mark it on the balancer to timing cover tang. Then grab a strip of metal clockwise from the tang, and mark off 35, 37.5 and 40 degrees using a protractor with the centre cut out so you can overaly it over the balancer.
Bump the timming up to 9 or 10 degrees at 1000 rpm with the vaccum advance disconnected. Then add the advance line back on, and make sure the total advance is over 38 degrees at wide open throttle.
