If your buying a 147, i think most people would agree, that unless you can afford to buy/run a 3.2 GTA, the best petrol one to have is the 2.0TS, but the 1.9JTD 16v 140/150bhp (not so much the 8v 110/115bhp) is a fantastic choice of engine for the 147.
the 147 is a great and fun car with a pokey lump, and the diesel although this doesn't sound like typical advice, being an Alfa JTD unit is a really really good performer.
arguably (this will start it off!) quicker than the 2.0TS petrol, more practical and flexible (you'll know how Alfa petrol motors love to be revved!) than the petrol, and miles and miles and miles more economical (none of them can argue that one!)
i'm not overly biased, i'll have a 51 Reg 2.0 TS 147 for sale myself soon in fact, but in all honesty, everyone who has the JTD 16v versions, love them!
good luck, happy shopping,
what an exciting time for yer dave, i'm jealous, and welcome to the forum.