I have a chance to buy a Gravely Pro 50 with 16 Horse koehler for a pretty good price. don't know how old it is but it has the single wheel in back. A friend has a small engine repair shop here and has told me we can rebuild the engine (if neccesary) for the cost of parts. How fast are these mowers? I've got 2-3 yards that are 2-4 acres and my 36" Snapper WB is really getting tired! Any help would be appreciated.