I was thinking maybe 8" on the back and 6" on the front?
 
I reckon it needs the offset more than the actual overall width of the wheel?
Once the arches are on, and I get an idea if the diff (BW?) should be kept or swapped, when we'll know how wide to go.

an update from weekend 5, the impromptu lockdown meant family commitments could not go ahead, so I unfortunately had to spend a fair bit of it in the garage.
 
Welding is continuing to improve.
I bought new tips for the first time, after getting a serious block.
My gloves looked like a bunch of burn snags, particularly the left hand that I use to hold the gun. 
Some clever bloke worked out this, so you can buy a pair of one glove.So I got some 'Lefties'
 
It seems like you go 1 glory job to every 5 if your lucky.
So this weekend I cut and welded on the front passenger bubble as the fun job. 
I used a handheld joddler? /punch from Metal Man tools for the first time. It chomped through the bubble arch easily, but the flange depth of the joggle isnt very deep, lucky if it was 10mm.
This meant the matching spotweld punch whole was corresponding closing to the panels also.
I thought I may blow through being so close, but all turned ok.
 
A skim of filler, then etch prime on the inside and out.
The crease fold down the hip line needs some work, as does each bottom side of the guard.
 
 
 

Your doing well there Deano, lock-in time is shed time! When Adel done it for 2x days I quickly steelo padded the ute and painted it the next day I painted it... In shed white enamel just so it's 1 colour, only used 1ltr for the complete cab but it's only till I do the full conversion sometime soon. On a good note I've got a buyer for the mk1 coup shell once painted that's been on the rotisserie dormant for a year so I will be getting back into that one

forgot the pics...^^
 
 
 

Woh, Deano, Glad you all escaped relatively unscathed, it always impresses me how well modern cars stand up to this sort of accident, even more so to a 4WD impact. 
I'm glad you are soldiering on with your project as it gives me something to enjoy catching up on. I have been making progress on the Capri however too slow to be worth posting.

Who puts up these stupid rules, need 5 fatalities, does the rta have a tally board with all road corners deaths... Just pathetic. But on the other hand if a mp gets dead on a corner it's instant restructure the roads there.
On a good note we're glad your still above ground and ok.

As with installing the new running gear from the broken car, the simplest way would be to cut the floors and bulkhead off both cars and swap lids over. I've seen this with mk1 Escort with a full Sapphire Cosworth 4x4 floor, his only complaint was wiper blade chatter at 176MPH !
A local Adelaide hills guy did similar in 1994 using a rolled Laser tx3 4x4 turbo floor mated to his mk2 Escort, the length was slightly longer but a chop in the less strain area and also a set of mild arches kept the Laser tx3 wheels tucked away, fast sleeper..

Didn't realize it was a Porsche.. I'd been working on a 2018 Cayanne the last couple weeks which is on its way to Perth now. I repaired the rear suspension so it was good enough to load on the truck/train..
Gotta say they are built rock solid. If you all was in a ve or falcon that corner would've got the quota to be fixed plus a couple spare..