Sounds like a very cool project. Best wishes with it. Similar to one we have planned.
Some things going into the 2.6 liter Type IV motor when time allows (so many projects to complete beforehand):
Type 1 Journal on crank - hard to find, but available 18 months ago when started assembling parts. Stroke is 80mm (78mm stroke crank wasn't available).
Nikasil cylinders with JE forged pistons, 102mm bore. Pistons are light, light lifters and valve train, along with lightened flywheel. Reducing reciprocating mass improves longevity, faster acceleration, more HP. Careful balancing very important.
Better than H-Beam rods (lighter and stronger):
https://www.thesamba.com/vw/classifieds/det....php?id=2342801 EMPI New Pro Series I-Beam Rods 5.5 Length with ARP 2000 5/16" Bolts in a VW Journal. These are lighter and stronger than the H-Beam Rods.
Aluminum push Rods, custom length.
Type 1 tool steel lifters (lighter than Type iv).
Custom cam with extra duration on exhaust stroke (helps control motor heat). Lead time can be a project killer though.
Keep compression low to aid with heat control. Initial spark setting,to be 14 degrees BTDC, with 28 all in...subject to tuning and optimization. Probably starting with carbs because they're so tunable and easy, especially since the car is already setup for them. Maybe later, like you, it'll have injection?
As you already know, heat is an enemy in larger Type IV motors. So, stay focused on that (in addition to careful machining and assembly) and can't wait to see how she turns out!