The flat 6 has its moments. They usually require the roof to be off and a natural tunnel of some description, even then, it's more heel & toe moments rather than flat out full chat. 911 of similar vintage sounds a lot better, so I have strong feelings it's exhaust based, i'm just looking at about £1,500 for a passable new system, which is a bit strong.
I have found a couple of cars - a couple of passable ones on Pistonheads, and two appeal to me from Clive's collection. Nothing that's completely hit the nail on the head yet, but a few possibilities for sure.
Seems decent cars are getting quite sparse. A serviced, Q2'd, xorsted, phase 2 seems a rare beast indeed. Or at least, well, it does for my price point.