Lister D Piston and bore.

Hi I have a Lister D another project.
When I got this it was completely seized from lack of use and poss stored outside, the guy that owned it used to show it up until about five years ago.
Now my quandary is, I remove the head after leaving diesel and oil mixed in bore gave the piston a good clout with piece of wood and she freed up
and turned over, the bore was covered in rust so spend a bit of time cleaning with fine sandpaper, the valves seat were pretty useless but thought put it
all back together to see if it will run, while turning over to get it started I started to feel compression and the more I turned her over the better it got
and this is with the valve seats very badly pitted, eventually it started and surprised me it ran quite well considering, I decided to get a new exhaust valve and head gasket
which arrived today and have cleaned up head and fitted new valve.
The thing is do I go all the way and remove the piston and give the bore a proper clean or do I do as much as I can with piston left in, which would save me a lot of time
and the fact it had compression and was not burning any oil is why I am thinking this way.

Any comments please

If compression is good, it's not burning oil AND you are confident there are no abrasive particles from the sandpaper stuck down between the piston and the bore then I would say "it ant broke so don't fix it".  I take it you don't expect to to be making it work 8 hours a day so it doesn't need to be mechanicaly new condition, Some people like doing it for the hell of it.  
I've heard of a light overnight rust being used instead of honing to help bed in rings, so clean it as much as you can.  
Ie turn crank so piston is at the top then squirt some solvent around between piston and bore, then sit it upside down (drain the sump 1st), and squirt some more solvent in around the piston while turning/rocking it and see what comes out.  That should tell you if you need to dismantle it to clean it.  Just doing that may be sufficient to wash any unwanted stuff out if you keep doing it till no more comes out. 
Any solvent that will dissolve oil, ie diesel, kero, meths, petrol, brake cleaner, paint thinners etc will do.  Make sure to oil the bore again soon after, especially if you used one of the "dryer" solvents ie the latter ones in that list.

Good luck
Cheers
Darryl

I would strip it down and clean what needs cleaned and reassemble after I had ground in the valves.
Time does not matter why would you want to save it?