I'd take Owen Coyle and Sandy Stewart, Coyle is proven down south and i believe his Ross County spell was a blip as he entered a shambles.
Other possibilty for me would be to give it to Stewart on a permanant for this season, see how it went, we could do a lot worse, plus what is John Henry doing these days, Stewart and Henry could be a good combo.
Complete fairytale would be Jack Ross who is seemingly about to get sacked at Sunderland and tbh probably will need to come back to Scotland to resurrect his career.
John Hughes been mentioned a lot but has built a reputation with falling out with players and his last spell at this level with Raith Rovers was a disaster.
Also Terry Buthcer?