The analysis provided by Adrian is indeed interesting. The par-66 would certainly be tough.....I doubt there'd be many low handicaps on such a track.
Jerry mentions the Postage Stamp, a hole that has historically been tough on pro-scoring generally, surprisingly so when it's short length is considered. But then again it does have a tiny, easy to miss putting surface, a challenging green complex, grizzly bunkers and the wind.
As to playing the PS at 220 yds, bogeys for all I imagine as almost all would miss the tiny green and fail to achieve an up-n-down. But what would it's SI be at such a distance?
This to me is a key question if you're playing what seems to have become the standard form of golf in the UK, namely one-round stableford or matchplay because most of the time par-3's have a high SI. If we assume that the average male hcp is 14, well a 14 hcp is not going to get a shot on SI's 15-18 so a tougher par-3 is probably going to be a 'dropped shot' stableford wise for Mr Ave-Hcp pretty much every time he plays it or a lost hole in matchplay if playing against a much lower hcpper. SI may not, as Jon points out, be directly related to difficulty, but for amateur handicap play SI is pretty key.
Normally there is only one SI pattern for the men's tees irrespective of colour of tee/length. Should there be different SI's for different holes depending on the men's tee colour (length) being used? For example the same hole could be say SI 1 from the yellows (as a long par-4) but say SI 15 from the whites (as a very slightly further back short par-5). Or it could be say SI 2 as a long, tough par-3 from the super back tees but say SI 16 from the upfront-yellows. Does this happen?
Atb