If it’s for one chainring I’d decide what size I was going to run and builld the bottom guide into the frame’s chainstay construction with zero adjustability, one bolt and a jockeywheel between the guide frame.. for the top I’d incorporate a threaded mount in the lower seat tube to bolt an E13 (SRS) plastic upper guide plate assembly straight into.
Reasons – mud clearance and stiffness. far too many guides suffer from problems when exposed to huge amounts of mud.. and all carbon BB/ISCG guides have been designed with weight savings as a priority and flex far too much.
if you think you might need chainring bash protection, incorporate two taco mounts under the BB shell/chainstay yoke