[vettestr]

What is your choice in terms of street or strip? For a strip carb choose the Holley 750 or a 780 double pumper with mechanical sec. This semi controlled fuel leak will give best times once tuned properly but will be at the expense of street performance and any MPG you have now. A better double use carb would be the Edlebrook AVS but more people have a hard time fine tuning this carb and if going this direction the Carter Comp series 650 that this is a knock off from is even better. This carb has some 37 possible adjustments and hard to beat if all correct. I was raised with the Carters and shown all the mods to fine tune this carb. The book about Performance mods for Carter is pretty good and lists many of the tricks Dad showed me years ago. For Drag racing only the Holley is more popular and more people can tweak it with you.
I would try 4 more degrees of initial timing to 18 and back off mechanical 1 or 2 if needed. If bumps against started when hot just stroke gas pedal once before turning key to flood a bit so it spins up before trying to light against starter