The only caveat is that the Space Horse has a very low bottom bracket, which makes it unsuitable for riding fixed on the road due to lack of pedal strike clearance in turns. The BB drop on the Space horse is 75mm, whereas it is only 58mm on the Big Block track frame, so the BB is 17mm lower, which is a lot. Add the likely use of longer crankarms and wider pedals, and you could have a problem when cornering. If you stay with a SS or geared setup, you will be fine, and I see nothing wrong with your choice.