Hi Andrew,
Not meaning to be rude, but what weight are you? I'm around 100kg & that's another good thing about the Challanger, I get to remain in the 10 rego classification by about 10 kg.
I was looking at repowering it with a HKS or go for a 582 just for getting for a bit more power up my sleve, but when I did the figures I beak the 300kg barrier.
It's hard to tell by the photos, but is your plane fitted with brakes? & How what's the rudder control like at low speed.
I learnt on a 912 Lightwing taildragger if that's any help.
I was looking at the Lightwing PR Bipe that's been for sale for a while, but the rate of climb etc, is not there, & the scary thing is that it's been advertised for years, yet the hours remain the same, and that worries me a bit.
I have noticed with yours, that although it's been on the market for a while, the hours keep moving upwards, so I'm confident it's not a time bomb.
Regards
Ron