130hp Fast Road set-up.

Though the chances of finding an untouched Turbo engine in good condition are rare, if you are lucky enough to do so then the standard Turbo pistons, crank,  & rods can be used {though new rod bolts should be used}, & are man enough for the job at this stage of tune.
The standard helical gearbox may be fine as long as everything is in excellent order. This means new bearings & and everything within tolerance, though probably on its limit & if the budget allows a SC item is preffered.

Head.
A nicely modified head with 29mm ex and 36mm inlets. It doesn't need to be a race specification head at this stage of tune.
The sodium valves do not need to be retained & can be replaced with high quality stainless items if needed.
The standard Payen BK450 head gasket is the one to use. Also add a set of new head studs. Drilling for 11 studs is not essential though may be worthwhile.

Pistons/Block/Rods.
As mentioned the standard Turbo pistons are a great item & are fine for this application. If they are not useable, a high grade cast piston such as the Omega should be used. There is no need to go to the expense of a forged item at this stage.
Use the ARP rod bolts.

Cam.
A good fast road cam will do the trick for this kind of power. Don't go to wild on the cam you'll only lose drivability. Suggestions - Kent 266 or the normally aspirated MG Metro cam which is ideal !

Timing Gear- Add a duplex timing chain. A vernier adjustable item can be used or use offset keys with the "fixed" type to time the cam in accurately.

Clutch/Flywheel.
I would upgrade to a steel flywheel & backplate. Use the Grey diaphragm & the AP rally/race plate.

Gearbox.
A twin pin diff is pretty much essential.
I would also recommend the use of a set of straight cut drop gears.

More boost.
Installing a decent intercooler is well worthwhile, though not essential at this stage as you should only need to run about 10psi of boost.
The compression ratio should be about 8.5-1 - 8.8-1 & does not need to be any lower at this stage.

Others.
Use a high capacity oil pump, high grade cam followers, good quality main & big end shells etc

Obviously this is only a rough guide, but with a correctly built engine you should see around the 130hp mark.