72 2.4, flat six Options

[CG-914]

Me and my dad are rebuilding a 72 2.4 engine.
They are some wired things going on with the parts in the engine so here are some facts and questions about them.

We are rebuilding the engine but also want to modify it.
Maybe different cams and make it a 2.5….

Engine Case
901.101.101.5R

Heads [Date?: 4x 72 + 2x 71]
911.104.306.OR [K 1819g]
Valve Intake 45 mm
Valve Exhaust 30 mm
Intake 37.5 mm
Exhaust 36 mm

The Intake ports are bored out. With that size are they even useable? also in regard of the plans? Are the valve sizes stock?

Cylinders [Mahle]
90 ZN 2 W6 [5x]
90 ZN 2 W5 [1x]
Diameter 84 mm
Total Hight 120 mm
Pistons [3 Piston Rings]
Hallmark 1: 83.95 [84 mm]
Hallmark 2: Sp 0,05
Are these the stock cylinders?

Cam Housing
901.105.111.OR
Stock?

Cam
left 901.105.183.OR [965?]
right 901.105.110.1R
Here it gets wired. With Wayne Dempsey's great book, I think this is a S and a L cam out of two different engines. Was that something a lot of people did?

Also the wear marks on them are pretty bad: See pics

Then the question about the 2.5 liter engine set up.
I understand, that they are two versions:
1: 2.7 liter as a high stroker
2: 2.4 liter with bigger bore.
With rebuilding a 2.4 what are our options to build a 2.5 exactly?
With what consequences? What needs to be changed/machined accordingly?

With that in in mind what cams are best?
As I read and heard the S cams are the best with now further consequences like taller intake manifolds?! Is there a great article about 911 Cams, they characters and consequences?

Thank you guys!