I have nothing against Schumacher – and have only heard great things about them.
That said, I have a bunch of NOS spool type big block engine mounts that I would like to use, if possible.
I also know that one, if not both, engine mount perches are in different locations and heights vs. small block – but not really found much published as to how much.
A plan I developed many years ago (but not implemented) was to perform some measurements and make a jig before cutting/welding (if needed). If I use Schumacher mounts, or not - K-frame modifications will be needed.
First, I was going to replace all three engine/transmission mounts on either one of my cars (both are 318 2-bbl 904/999 car’s) with new so measurements should be accurate.
I have plans on going solid (or poly) K-frame mounts – so can not use the K-frame bolts as measurement points. Need to pick another location to get get height measurements on all 4 corners of K-frame as well as transmission mount to ground. I’m thinking the transmission mount flange might be best location as well as slip yoke (top and bottom) measurement to ground - sense transmission mount location might not be the same on A518 or 5/6-speed manual transmissions.
Also get a crankshaft to ground measurement, a crankshaft to Left and Right frame rails and slip yoke to Left and Right frame rails (or something fixed to measure from).
Once measurements are made, make a jig using a spare small block K-frame I have – so I can place a big block (crankshaft centerline) in same exact location (to keep propeller shaft vibration(s) to a minimum.
Part of the jig is to also get a used transmission crossmember (upper part, or the part welded to floorpan) as part of this jig
My original goal was to put a built 727 into my Fifth Ave and a 5 (or 6) speed manual in my wagon. I was needing to know what/how to modify floorpan and rear crossmember for the manual conversion – for I need to keep the "down time" to an absolute minimum.
After seeing your A518 install, I’m leaning a lot more towards that direction – which again, having the rear crossmember (upper section) as part of my jig, should help on that portion, as well.
I do have slightly different goals with my big block conversions than what other people have.
First, cars will be daily driven and will not be show cars (not that I might not show them) nor race cars (not that I might not take to drag or road race course once or twice).
My goal is to open hood and at first, second and maybe even third glance, for cars to look like a plain ole small block – so nothing to see here.
With the Fifth Ave, I want the factory black air cleaner in place with a (faux) Lean Burn computer hanging off its side, (working) factory A/C, cruise, and so forth. A 4-bbl throttle body fuel injection, exhaust manifolds (mainly for looks and to reduce noise). I also want cars to be as quiet as all possible (for long trip pleasure, and for other reasons). Engines will not be built for high RPM and hoping everything will be happy with shift points around 5 to 5.5K RPM. Peak torque way way down low.
Something my wife will be able to drive and have no complaints about driving - if she needed to.
Anyway, that is my goals – just need to “get it done”.
BudW