Help - updating Space Crusade

Hello,

Just before Christmas I had a bout of nostalgia and wanted to create an updated version space Crusade using the original rules and missions, but updating the mini figures and game board.

I love the imperial fist terminators space marines, but they come with mostly storm bolsters and I want to use weapons that are closer to the original like missile launches assault cannons and plasma weapons.

Does anyone know where or if you can get replacement weapons or arms for these mini figures?

PS. I’m in the UK