I wouldn't spend too much if your getting EFI soon.
To rebuild and fully tune a set of Solex you're looking at around $700+. Mind you, afterwards you think it's a new motor. Best money I've spent on the old girl in a long time.
And, if you need this done I suggest you take it to Frank Kleinig - though I did hear through the grapevine that he's now retired. That's a bummer, who's gonna be able to tune these mofos next time?