Joka, lighter is always better when it comes to the "Engine compartment". My recommendations would be (in order):

BME55 (when available)
BME50
DA50
ZDZ50
BME44
ZDZ40
go glow

Most of your Sachs/Husky based engines, especially the industrial-based ones with minimum modification or lightening, will come out a LOT heavier than any of these engines, and make substantially less power. Any engine that adds more than 3.25-3.5 pounds TOTAL weight (muffler and ignition included), unless it makes a substantial amount more power than the above listed engines, will only degrade total performance. It may make it fly fast, but it will then be a very fast flying brick.