4:1 mast climber

[ExTerra]

As we age we find we need a little more help around the boat. We currently have a 3:1 climbing system with Brian's harness. Our climbing system uses single hexaratchet blocks (one with becket) and a climber's ascender with 1/2" line. To heft our aging bones we want to change to a 4:1 mast climber.. Do any of you have a 4:1 or can you recommend blocks and line to make a 4:1 system?

s/v ExTerra IF38C