Some of the webers installations have hard cold starting problems. I've never been able to completely figure it out, but I've put Qjets on a boat and the problem went away.
But if yours is a warm start issue I would make sure it's the carb that's the issue, not ignition, etc. If it's the fuel boiling out or vapor lock, you might have the same problem with a new carb.
You might have a spreadbore manifold now with a squarebore adapter. If that's the case, the most reasonably priced would be a used marine Qjet. Rebuild it, bolt it on, it shouldn't need any tuning. The only modifications would be a new hard fuel line and bend or the choke linkage rod to work without the spacer.