The 850 block is different to the 998 where the dipstick goes in.
If you have a dipstick tube it's a 998 (or 1098), if the dipstick goes straight into the block it's an 850.

Trying to determine what block I might have...
It is in a 69 Morris Mini from New Zealand. It should have had an 850 in it but not  convinced it is since I cannot find anything that confirms this.
It is a pre A+ series block for sure as it has the tappet covers.
There is no tag attached nor is there anything stamped in its place...
Have not checked casting # on head yet.
Heater valve is 90 degrees to the valve cover so it should be a small bore
On rear of block (clutch end) is casting # 12a497 and just under that is J5073
I read where the 12a497 is a generalized # for some of the small bore blocks. But what about that J5073# what’s that about...
There are no raised casting numbers anywhere else. I looked for the 850,998 or 1,000 numbers on the other side toward the radiator already with none found.
Doesn’t look like it had a tag back there either..

Any ideas on where to go now. Or other things I can look at to narrow it down...Not willing to remove head and measure bore at this point...