JLW,
The older engines needed leaded fuel to lubricate the valve seats.
I had a 1965 F-150 with a 352 2V carb it ran great on cheap fuel
(85 octane). How many miles are on the engine? Has it been rebuilt replaceing the valve seats to hardened ones so you can use unleaded fuel? Check the timing chain to see if it has "jumped". Maybe you have a lot of carbon build up on the intake valves from "little old lady" driving habbits. An old mechanics trick I know to remove carbon is; get the engine up to operating temp. and slowly pour a can of "Classic coke" down the carb. 1 can in about 60 seconds. Holding the engine at about 2000 RPM. I remember the dwell reading was very critical. Useing a dwell meter the engine didn't run very well but useing a match book cover or feeler gauge (.016 or .015 I forget) to set the points the truck ran great. Hope this helps.
