1983 1.3 Formula E OHC Engine Head

After my polo has had trouble maintaining ticking over when inbetween hot and cold, and general uneven tickover at every other time, and many attempts at mucking with the lovely pierburg and ignition, we decided to adjust the valve clearences.

We discovered that the cam shaft above cylinders 3 and 4 were badly worn. 3-4mm down approx. So I must presume that the valve followers are also as badly warn. This looks like it was due to the oil pipe thing being blocked, which we have now fixed.

Can anyone tell me whether:

1) This would cause the rought tickover 2) If I get the entire head off a scapped car, will a 1l one fit the 1.3 engine. 3) Would it matter if it had hydraulic tappets in? (Mine hasn't)

As you can guess I dont want to spend much on a car that aint worth much, but it passed its MOT a few months back no problem (although they said the tickover was rough, so dunno how they tested the emmissions) so loath to have to replace it with another banger for A-to-B driving.

Thanks

3 to 4 mm of reduced valve lift,on only two cylinders causing a bad idle? I think so sir! Can't quite remember which engine was a bored or stroked version of what other engine, but the camshaft timing and probably the valve lift of the 1.0 litre will not suit the 1.3 litre, even if it does fit. The other point is that the Formel E engine was higher compression than standard. I am sure that hydraulic valves came in UK VW's about 1985 /86, along with a better oil pump, and that is the important thing for the hydraulic valves. The pump driven off the crank on the pre 86 engines,wouldn't be good enough for hydraulic valves. The best thing to do would be to put in a replacement camshaft and followers. That can be done in the car. ( Timing belt and pulley off, distributor off, remove cam followers, slide cam out etc.)