Tom, i have no experience with a frame-mounted TANAKA.
But think about it. The TANAKA is almost half the size and weight of the HONDA GX50. If this engine has threaded bosses underneath, it should be a simple matter to drill new holes and bolt the TANAKA into place in the GRUBEE'S motor mount. You may or may not have to raise the engine to align the gearbox and rear sprocket.
everything else is elementary, my dear friend, elementary.
I gotta say that my only mechanical experience previous to my presently busted bike is changing brakes/alternators/starter/waterpump/ on a car. (And adjusting the fuel mix and timing on one very old chevy.)
I've haven't seen a Tanaka or Honda engine, or a Grubee mount, except online, but what you're saying is that I can pretty much put anything in my frame that'll fit in there?
I suppose I'm also limited by the two clutch sizes (50-something and 70-something mm) and/or the drive shaft widths? This will be my first time to delve into those parts of an engine....
Tom, the smaller engines generally come with 54mm(?) clutch, and the 32cc or larger motors use 76mm clutch. the HONDA GX50 and larger engines may need a STATON adaptor to fit where 76mm clutches fit.
generally speaking, fitting engines in frame and rack-mounted locations is one thing. GEARING them to provide fair-to-maximum power is another.
Your 70cc engine is blessed with 4.1:1 gear reduction at its sprocket. that allows a smaller(30t-48t) driven sprocket. without this 4:1 reduction, the rear sprocket must be 123t-197t to attain that same gear ratio as the 30t-48t sprockets.
That is why the GRUBEE box is used, to provide gear reduction to facilitate the installation.