Howdy and welcome.

I ran a ST3000 in mine-- but I'm in Denver at 6000'.

A 150 Saito isn't going to give you unlimited vertical. For that your going to need at least a 180 engine.

The Moki 180 or 210 would be great. Or even an MDS 2.18.

I'd stay clear of the chainsaw engine in this plane. It's too heavy and not near enough power for what you want to do.

Unless you put a Poulan 46cc in the plane-- now that would be unlimited vertical..

Be careful with this plane. They build out tail heavy. Mount your engine first and then locate your servos.

Servos in the tail are out of the question unless you put a huge motor up front.

Good luck with your project. Let us know how it turns out.