S80 B6284 T6 into N/A LPG Performance Build

[tripleXsix]

So i bought a B6284 T6 engine 1999 with 70k on it for cheap with the intention of swapping it into my beloved 960 2,5l estate 1995.
But, after a lot of contemplation, i ditched the idea of turboing this car. Mostly because in the mean time i had the car converted to LPG ( a BRC system) with a 110 liter tank in place of the removed backseats. No noticeable changes in engine output and behavior, just saving around one euro per liter compared to pump gas. But LPG does put on a higher thermal strain in the combustion process and i just don't want this in combination with a non standard turbo system.
I need this car to be 100% reliable as she was for the past 60k miles that i owned her.
I also still need more (low- and mid range) torque and horse power.

Now, the easy and economical way would be to swap in a B6304 + headers + 200 cell cat (already have 2,5" custom catback).
That would get me somewhere around 225 hp and 310 Nm i guess, which would, combined with the 4.1:1 final gear ratio of the 2,5liter and lightened 960 with autotrans, already be slaying a lot of Audi's and Beemers at the traffic light.

I would however, miss out on the goodies of the T6 engine already in my possession, strengthened block, improved cooling circulation, lighter and knife edged crank with squirters, better flowing head, lighter valve train with sodium filled valves.
So i want to rebuild the T6 into a reliable atmospheric LPG performance engine, favoring low- and mid range torque.

As i understand the T6 is essentially the 81mm bore of the 2,5 liter straight six (B6254) combined with the crank of the B6304.
Compression ratio of T6 is 8,5:1 while B6254 and B6304 have a cr of 10,7:1.
LPG octane varies from 100 (summer) to 104 (winter) so the cr could possibly be raised to 12:1 with out detonating, please correct me if i am wrong.

I have as of yet no dimensions of the T6 rods/pistons, as the engine still awaites shipping from Scotland to Amsterdam, Holland.

So what would be the best approach to achieve this cr?
Would replacing rods and pistons of the T6 for B6254 parts achieve this in combination with planing the T6 head?
How much can the T6 head be safely planed off and what would be the consequences for distribution timing?
Would the T6 cams achieve my quest for low- and mid range torque?
What about the VVT on the exhaust cam, how can it be controlled?
Would the original 960 2,5l Motronic 1.8 ECU be able to run this build?