Now you are talking into a category I know well!
The 156 V6 has MOST of the performance of the GTV V6 with MOST of the practicality of the 166 V6. The 156 2.5 V6 lump comes with 190BHP and a 6 Speed manual gearbox. Not really into stats, but the 156 V6 clocks a 0-60MPH of around 7 seconds or under and can do a touch over 140MPH.
I've had 2 and SWEAR by them, plus you can get a much better example closer to home for alot less as the GTV V6's are alot rarer and therfore go for alot more money.
The one you want to get mate is an early model Sport Pack 3 edition circa 98-01. These came with side skirts, rear spoilers (Some came without the spoiler though) 16" Tele wheels, carbon dash, leather steering wheel, and MOMO leather interior. But, most importantly, they came with upgraded suspension which had them hanging to the road like GLUE!
You can get a MINTER for less than £2000 nowadays mate, they are fabulous cars and if you don't get a GTV V6 then your next best bet would be the 156 V6.
Cambelt and servicing is identical if memory serves correct, so they don't cost any more or any less to run than a GTV V6, but due to 500cc smaller engine you might get better MPG???