New twist on the classic "will it fit?"

[hemitheus]

I have a 74 Standard stock height. IF i go with...
Wheel Size: 17x7
Tire Size: 205/40
Wheel Offset: 42mm

What width wheel spacers would i need to prevent knocking components inside the wheel/tire

and

WHat size widened fenders would i need to fit the wheels?

I have tried the calculator mess but it just doesnt click in my brain.

Also... would i be able to lower the car any without messing this all up? If so how much?

Id appreciate as much help as you guys can give me

[Typ Vier]

I fitted the GT3 brake to a ball joint front end and had issues with the clearance between the calipers and the 17 inch wheels. Wheels are/were 996 BBS 7x17 50mm offset. I fitted a 2 inch narrowed beam and then added porsche 25 mm (1inch) wheel spacers. This cleared the calipers a little more and also gave more room on the inside of the wheel to the axle beam.