I need your advice

[68caddy]

Hi guys , I am new here and I want to ask your advice.
I have started frame off restoration of my 1972 Gmc , it was a 3/4 ton longbed , but previous owner cut the frame , and put a short bed on it. He also installed a five lug , ten bolt rear end . The front suspension was swaped too and thats why I am asking your help.
The control arms shafts has a rubber bushings , so I think the control arms and spindles was taken from 1973 up 1/2 ton truck , but I have no idea , what about rest of the stereeng and suspension components I want to replace new
Let me know please, which parts should I buy for a 1972 3/4 ton truck and which , ( except control arm bushings of course) , for 1973 up 1/2 ton. Look at the pictures please , maybe you will know what kind of parts my truck needs.
Do you think is complete crossmember swaped?
I live in Poland , ( Eastern Europe) and really appreciate your advice , couse I have to be maximum sure what I will buy . There is no returns or exchange the wrong parts in my case , so try to help me solve this problem.
I know guys , my language is not the best ,so sorry for all the mistakes.
If you need more pictures , let me know , what you need.
Thank you and regards!