There are going to be numerous complications/expenses to installing a 670 Predator into a bare (no engine) 3016 chassis. Here are a few I can remember off the top of my head..... As you'll see below, the additional parts you'll need for that bare chassis beyond your 670 Predator are not cheap.
1) You're going to need a flywheel "stub shaft" for a 670 Predator to drive an electric clutch --- $150
2) You're going to need an electric clutch and fabricate a torque plate --- $220
3) You're going to need a Lovejoy coupler to mate the engine PTO shaft to the Hydraulic pump shaft --- $75
4) You're going to need a mounting bracket that couples the Hydraulic pump to the back of the engine --- $100
5) You're going to need a 670 Predator exhaust manifold that exits 90 degrees to either the left, or right side that's long enough to clear the hood --- $140
6) You're going to need a muffler that fits the diameter of that exhaust manifold with a heat shield that keeps from scorching the hood paint --- $100
7) You're going to need a 12VDC electric cooling fan that will fit between the oil cooler and the front of the hood to keep your hyd oil cool --- $75
I understand using an engine you already have, but don't think you're going to gain anything in the way of "power" by installing a 22HP engine over the OEM stock 16HP engine. It's a full hydro-drive tractor, the CC displacement/GPM flow rate of the OEM hydraulic pump is what delivers the "power" not the torque/HP rating of any engine you install. The only thing that is going to happen with instaling 22HP engine is you're going to be applying way more torque to the four 3/8" bolts that are holding that 3"+ stub shaft to your flywheel and that comes with it's own set of stress/shearing problems when the clutch loads and you start driving a mower deck, or snow blower
That 3016 chassis should have a factory installed "holding valve" on it, all INGERSOLLS did.... It was the CASE tractors built prior to 1984 that you could have an "Oh Sh!t" moment on a downhill grade if you didn't read the operating instructions, and you didn't buy the "holding valve" as a factory installed option.
It's usually way cheaper to find an Ingersoll 3016/4016, with either a good running (or even an OEM engine that needs rebuilt) than it is to buy one that you try to "re-power" with any engine other than the stock OEM Onan or Briggs engines. Depends on the year.... Up to 1992, OEM engine was a P216 Onan. After 1993, OEM engine was a Briggs 303777 Vanguard.
