If that in-line compound engine is anywhere near as well built as it looks like it should be, then it could actually be worth quite a bit, as in four figures easy. If its potential value is of real concern than I would certainly recommend against any ham-fisted novice attempt at restoration. A true Steam Mechanic or good machinist may be what you need, if you are not such yourself. This is most definitely not an engine that would be easy for a beginner to learn on, but if you could source a serious model steam builder/collector to mentor/tutor you, then you may find this to be an incredibly satisfying learning experience!