Have never heard of anyone using a TS as a track Car ! Most people just use the 3.0 Litre.
Seriously if you want a proper track car start with the V6 don't even bother with the TS it has no power. Im assuming you've never driven a V6 ??
Ive owned both TS and V6. The V6 Feels like its got almost Double The Power of the TS with Power all the way through the rev range.
And if you think it cant handle corners well the TS might have an advantage over slower corners but the V6 Easily Blows the TS away on the straight by a Long Way !!
Except by the time you port the heads (which increase air:fuel into the engine; and thus, power), add a stainless exhaust, powerflex the rear, shed weight, upgrade the brakes and suspension, the TS will be a clearly faster car around the track and will cost less too. Its a win-win scenario.
The V6 is far too front-heavy and yes, it will win on the long straights but if you know anything about racing and tracking cars, corners are where you make the most time. This is where the TS will come in to its own. Especially if it is specifically setup for the track. It will cost less, lap faster (not overall top speed, but LAP speed), be easier to maintain, and overall, is a great little option for a 916 track car. Obviously there are definitely better track cars out there (RX-7, MX-5 just to name a couple) but if OP is hell-bent on a 916 track car, the TS is the only way to go imo.
Not to mention if you wanted to get really serious you can head down the custom turbo mod route along with full dyno tuning, boring the engine, high-lift cam etc. Whilst I wouldn't ever bother doing this as its just throwing money down the drain unless you want to participate in targa races and the like, its still an option available.
In fact there are quite a few Alfa TS cars that have participated in the Adelaide Targa Rally over the years; never really seen many 3L's (probably due to front-end weight).
So honestly mate; I'm sorry but out of the two, the TS is a better track car. As I mentioned in my previous post, all these mods can be done to the 3L as well, but that is going to cost far more not to mention it still doesn't solve the issue of front-end weight that the 3L struggles from. Though to be fair, the 916's aren't really track cars. A Mazda Mx-5/RX-7 would be better options imo but if OP wants a 916 track car; get the TS and mod it. Cheaper, easier to maintain, and on the vast majority of tracks, you'll see a faster lap time compared with the 3L for similar money invested.