79 3.0 SC Tweaks?

[PMNorris]

Hi,
My 79 3.0 SC engine has had a few tweaks, but it's smoking a bit and due for a top end rebuild, so I intend to squeeze a few more horses out of it whilst I'm in there.

Current set up:
79 SC, Carrera chain tensioners, 40MM PMO's, MSD ignition, Distributor recurved for the PMO's, Turbo valve covers, SSI's, Early exhaust, Heavy duty clutch.
I think I've done pretty much everything I can do without opening up the case.


The 79 SC engine has 180hp and CR of 8.5:1.
The 81-83 SC RoW engine has 204hp and CR of 9.8:1.
The 83 SC RS engine has 255hp and CR of 10.3:1.


P87 of the engine rebuild book, it states that I need to have pistons modified for the valve clearance if I use early S cams.
P113 of the engine rebuild book mentions one of Wayne's top engine picks, the 'High Performance 3.0L' engine. JE Pistons, 10:1 compression. 36mm ports (according to the book I have I 39 and E 35).

I've been exchanging mails with Richard Parr at PMO regarding the highest compression I can get away with the 40 mm carbs (as they were new about 1 year ago I don't want to change them). Consensus is that 9.8:1 will work for sure, but 10.3:1 might be too much.

However, I live in Switzerland and can buy 95, 98 or 100 gas at most gas stations. I intend to drive the car on the road with occasional track days.

Questions....
- If I go with the 9.8:1 pistons and S profile cam, will I need to modify the pistons for valve clearance?
- Does anyone have a view as to whether the 10:1 JE pistons will work with my 40mm PMO's?
- How can I tell if my existing cylinders are Nikasil and how do I ensure that the replacement pistons will work well with the cylinders?
- I've been told that I should get my rockers reground/hard welded to ensure they work properly with the S cams. Are there any other mandatory mods? I'm assuming that new valves and springs are necessary if I change the port size?

Many thanks in advance.

Paul