whooligan
My old man had a Hillman Hunter Safari Station Wagon.....The only passport that had as a bus ticket. The engine literally fell out. Broken engine mount on heatherton rd.

My neighbour had one of those, and a friend had a Hillman Hustler, which was much more fun and I gather was quite a rare car.

spud15
pull the heads and sump off and have a squiz - god knows when it was last started, I wont even try to turn it over...
 

Have you done this yet?  I must be missing something.  Pulling the heads off will disrupt the gaskets and only show you the piston tops and some of the bores, not the rings, and you will have to machine the heads before putting them back on if you want to start it.  Dropping the sump will only let you see the bearing caps. 
 
I cant see how doing this will help you figure out if its safe to turn over the engine without stripping it further, in which case you might as well just leave it alone or rebuild it.  What am I missing?

Im open to suggestions - its been such long time since this one was started - id hate to install it and find it had problems (water etc in there). I wouldn't get the heads machined - just re fit them if they look good. Id probably remove some bearing caps and have a look at them as well.....

If you want to inspect the bores (at least the top halves) it might be better to buy one of those inspection cameras like this one: https://www.jaycar.com.au...reless-screen/p/QC8712

That way you can see the same as you'd see removing the heads, and you wouldn't have to. If it was me, I'd pull the engine down and do a refresh at least, with new bearings and rings and some basic machining. At least I'd know for sure things were ok.

I am no expert in starting old engines but I was always told to put diesel in the bores overnight and then turn by hand.  If it turns then next do a compression test to check rings.  Then fill and pressure test cooling system.  The worry is the condition of the rings and there's no way to inspect them without a full tear down, but if it passes a compression test then they are probably ok, but its always a risk. 
 
Again I don't know for sure but have always been told to never put heads back on without a skim first.  Chances are the manifold will be corroded so once you remove it its not as simple as just bolting it back on.
 
If there is any sign of water in the oil the a full tear down is a must.
 
But I agree with cosworthfreak, I would just bite the bullet, pray its not already taken out to 60thou, and rebuild it at the end of the restoration.
 
Hope this helps.

If it is bored to 60 thou and you run it then what are the options. Sorry to hyjack the thread but if you ran it and damaged it thinking you can rebore, to find its already got 60 thou pistons what next. I always have wondered about the RS3100 and what people do if a rebuild is required. They are an expensive motor to rebuild so to rebuild if not required for a motor that usually lasts a long time is costly. Certainly for me the difference is a numbers matching engine and what can be done. Sorry Spud.

put sleeves in I guess....
 
(I do have one of those cameras - but it didn't really work out very well - inspecting the bores.
I wasn't able to manoeuver it well enough - and the picture wasn't the best quality for determining the condition of the bores or valves..)

I've never heard of sleeves for an Essex block. Mine might just get away with a hone but then what to do. The RS 3100 must hold the answers.

Sleeves are shown in the parts manual and im told were a common size and still available

Yes you can sleeve them in theory but unless you had a matching block on a very tidy car, the cost would be far too excessive