Opinion Honda cr 125 on my domi 89

well, if you can access the 125 bike it should be easy to get some measures: swingarm pivot point width; distance from pivot bolt to leverage frame bolt; width of the leverage rod at frame bolt etc.

this can give you a rogh idea of what has to be done to switch the parts, if compared to the dimension of OEM stuff. but...

the 1989-90 Honda Showa forks were considered, by everybody who rode them, as one of the worst forks made by that Company, so I wouldn't support that choice: these forks were harsh, difficult to be accurately set up, and only a good service job made by a suspension expert could made them work in a barely decent way.

if you have an '88-92 Dominator, then the shock will be for sure way too long for a Dominator frame. this is due to the fact that the Dominator has a lowered shock bolt, so the shock itself is only 340 mm long - while a CR shock is around 380 or more. that's too much difference....

IMHO a deep search on ebay or similar would probably get you a lot of results for an Africa Twin fork - or White Power 4054 or newer. less pain, less welding, less machine work needed... only switching the steering pipes and obviously the steering bearing.

for the shock it's a bit harder, but if I found a dedicated Wjite Power (coming from an old Pharaons Rally bike)... you'd better trust some luck too...
anyway, a suspension specialist can change the oil and revalve your original shock with good results for a small amount, so it's a nice initial option - while searching the good one.

last: you write in English but this is an Italian language forum, so you'd hardly found somebody somebody able to answer you in English. it's plenty of high-level forums in English, why are you do writing here?... just curiosity...