Nice looking motor. I know some folks will howl but I agree with you on the 600 being "large" for the 283. But I also think the 390 will be small. I use a Barry Grant 525 cfm and am probably one of the few who will praise the carb! It's extremely responsive and very tuneable. I have had the same carb on my stock 302 and now 347 stroker, it's size has given it a good balance between power and economy also.

Don't discount the choice if you find one, you could be pleasantly surprised...