Not to hijack this thread but I hopefully my question is close enough (if there is a problem let me know and I will delete this), considering the Colonels comment about swapping out the front rings.
I have a '82 Miyata 610 with the same crank setup shown in the OP, SR 5tg triple 52-47-34. I rarely find myself up in the top 52t ring. Would it be workable to ditch the 52, make the 47 the outer ring and then use say a 39 - 30 for the middle and granny rings if I could find them? Or is there something geometry-wise about the middle 47 ring that it would not work as an outer ring?
I don't have an answer for the OP, mine still has the original Suntour BL FD that works with no problems.