Topband: matching elevated vertical

[Steve Flood]

I am setting up a balloon vertical (136 ft. radiator) with a feedpoint at 30 feet above ground and 4 radials about 60-foot long each.  I'd like to do something at the feedpoint to transform the 56-j115 impedance (modelled) for 50-ohm coax feed.  Is there a simple L-network calculator anyone has used?  Or is there a better way alltogether to do it?  I did notice in modelling if I lengthen the radiator to 152 feet I can get a feedpoint Z around 75+j0, but still needing some sort of matching device.  Any tips?  More and/or longer radials? I could probably go out to 80 or 90 feet on the radials if I really had to.

Steve, KK7UV