normally don't see blended stuff like this and if I do we correct it with all the right parts

have springs in stock if I remember I will measure a set tomorrow New ones

my guess your ride issue is spring pressures

 

That would be awesome! I cant find any thing searching p/n 45837-77, as far as length goes. Only diameter.

 

Here
Stock H-D fork Tubes length
Stock '49 - 77 FLH = 20"
Late 77 - 84 FLH = 20 1/2"
'84 and up FLT/FLHT = 20 7/8"
'86 and up FLST = 22 7/8"
'80-83 FXWG = 24 7/8"
'84 - 86 FXWG = 24 1/4"
'84 - 99 FXST = 24 1/4"
'92 - 99 FXDWG = 24 1/4"
2000 up FXST/FXDWG = 24 1/2"

Ride Height may vary if Non O.E. components or Different Year model components are utilized..
ie Tube length does Not Control Ride Height singularly..

 

Are those lengths for aprings, or tubes?
I did find a measurement for progressive replaceme t springs, that are supposed to be factory length. Progressive has those at 15.75" long. Which would make my springs 3.75" too long, if the 15.75" length is actually the factory length

 

Tubes...
I Have springs lying about and use what I like... and, as stated... I generally include a rebound spring in Any fork I re-assemble
I will modify my Post

 

Is #21 on the diagram the rebound spring?
If so, I have that. This is exactly the front end i have

 

^^^ Yes number 21 is a rebound spring,,, and, if I was ever in there.... it would be there... been a few years since it was new... so...who knows??