The donor car suggestion is no more that because NOBODY will get the complete parts for sale to make the conversion. Normally you could get around the regulator, glass, moldings, more to make replacement parts because some damage but maybe not the chanels ( or all of them ) or every bracket and bolt needed.
Beside that you will ne to find the matching interior parts, upper panel, sail panel side headliner moldings... thats also hard because beside get the part it self need the color AND the panel kind ( brougham or regular ).
If your SE is brougham what is the common, FORGETT IT, you won't find a brougham rear upper panel to hardtop WITH THE THIN WOODGRAIN INSERT. If you still think on make the conversion being a brougham interior, my advice is get a FULL SET OF STANDART upper panels on all 4 corners
I have seen JUST ONE car with Brougham interior on a hardtop on all the web all these last 6 years that I have been on Charger world websurfing being member of this beloved board... and that interior is now on my car

. Was on a Canadian car
I'm not saying find brougham panels to hardtop will be imposible, but ALLMOST!!!
you will get all the help needed to make teh converiosn, no prob, but trust me will take lot of time consuming unless as stated get a donor.
honestly, I would try to get the real deal, since will be also more valuable. Hardtops are more wished nowdays than SEs