I you search a little with key words like "
INQ 28 conversion" you will find a lot of conversions for inquisitorial retinue, including Crusaders. There are a lot of bits which can be used :
* power weapons are not to hard to get
* shield / stormshield are common in Adeptus Astartes line but plasticard + greenstuff / milliput can work too
* Scion chest is quite good for crusader if you got some spare, lighter than power armor ; Genestealers neophytes hybrids body and legs are good too
*
AoS / WarHammer high elves legs are quite good since you got knee armor and chain mail
* Head can be from lot of
GW lines but Kromlech and Victoria Miniatures can provide very good alternatives ; within
GW range I would go for Sicarian Infiltrators or Ruststalkers heads
* Marines arms without shoulder pads and little greenstuff / plasticard
Crusaders are quite open for conversion so you got a load of options.
Exemple (not mine) :
https://www.pictasite.com/post/BlV1_GrjdQz