What size bore ?
For the edrumergated there is a great difference between a opposed engine used in ga and the large radials used in a time since past. While they both suck push bang blow thats basically where it starts and finishes.
The airlines did not invent running lop btw. It was used by the millitary mostly to cross the pond to the UK for delivery. In fact there is a great book on it were they were running lop and had to go to rop to make it.
There are no free rides everthing has its costs.