Lucky you for having The film cutter guy! I had to buy my own on Ebay. But still, If he cuts perforated 70mm to 120, you are short 1mm on width. No problem for the camera magazine, but for loading in the reel. Unless he is cutting just one side off and leaving one row of perforation and right width of 61mm.
In the last year or so I'm saving all of mine used 120 backing paper and rolls.
Quite interested in Ilford 70mm run. Magazine I'm using is taking perforated film, but i heard that using non-perforated film in it is OK??? Looking forward for their prices?