I thought i was getting a great deal. A Hustler mini z with a gvx670 (600hrs) that needed a little work. Bad motor. But the shop owner gave me a "new" gvx630, said that he'd robbed a couple parts but they would interchange. Tore down 670 and have 2 broken piston rods and broken camshaft. A couple nicks in the block, but overall looks fairly unscathed. Parts will cost around $750. Start to look at 630 and realize there is no intake, exhaust mani., missing coils, missing stator. Cost to secure these parts is about $650. 630 is almost new, run barely long enough to put soot in exhaust port, but only rated at 20HP. 670 has 24HP and is setup to go on the machine. Which motor should be invested in? I am new to this and have never dealt with Honda small engines. Thanks in advance.