After removing the heads off the engine, they were both skimmed, both were out pass side by a max of 16 thou......OUCH

Great i thought i can get it back together......new gaskets were ordered and a few other bits and pieces, and i began re fitting everything after a good old clean. Low and behold the bolts stripped in the 3 main bolts on both sides, after helicoiling them drivers side is perfect pass side i still am having problems with.
The No1 bolt in the centre has stripped, upon closer inspection i really think this engine was slapped together to get sold. Being as all head bolts were soooo loose when i removed pass side head, and also its a 14bolt head/block pattern and what is now baffling me is that there is a chamfer on the bolts just below the head. On rimmer Bros they say that if there is a chamfer then the bolt is a stretch type.
Now im really confused........14 bolt engines as i thought were earlier than the ten-therefore not requiring stretch bolts.
What would you all recommend, as i havent fitted the lower set of bolts in any case:
Buy new stretch bolts
Buy new non stretch type bolts.
There is no engine number on the block and the car is a mk2 cortina that som people remember from a write up in classic ford and it used to run NOS, reg number CNO697G.
I really dont want to strip it down completely as i fear that there maybe a crack in the block and wanted to "test" it by getting the heads perfect and re assembling.
Your thoughts/guidance please.....im at the end of my tether.........