My vote would be for twin com .. believe lo-presti did some rather good go faster/less fuel mods ? .... that said there is another one well worth a look so long as all the AD's are done, I'm also unsure on the spares situation .. that is the Partenavia P68B /C.
Operated one in the 90's, very fuel efficient, great load carrying ability, good field performance, all round performance very similar to the Pa34, and good visibility, benign single engine characteristics, fixed spring leaf landing gear is also hard to break !! big drawback on a hot day was the cockpit became very warm if no sunshields were fitted, otherwise it was an absolute joy to fly.
The early AD's were to do with clumsy riveting of the firewalls after that pretty minor stuff..
bit more research it seems they are still being made, therefore spares support is available
Vulcanair Aircraft - Fine Italian aircraft design and manufacturing in the general aviation business