On the matter of weight: Last weekend I just saw a 2,0 type 1 with Oettinger Nikasils (90 x 78,4) that weighted (are you sitting?) 85 kg and produced 211 hp at the dyno at 7000rpm with Porsche cooling, custom exhaust with motorbike silencer and fan belt on.
Engine has a compression ratio of 10,8 :1 , DTA efi and will be used in 'dirt racing' (space frames).
Mag case and alu cylinders save a lot as well...
One other thing to think about
: the ligther your car, the smaller your brakes can be. Try a avoid heavy porsche vented rotors if weigth is your goal.
Light weight stuff is about as costly tho as more hp
Greetings,
Walter