Solder the battery terminals you can get to. The two for the battery and negative one to the block. Dip the terminals in muratic acid to clean them up and do a good water flush. Some flux and a big soldering iron. Can make a big difference.
number17610---------it is a toyota starter and you just use the motor section and the end cap with the brushes. starter motor up grade | R3Owners
there are a lot of threads on this if u type in starter in the search box.
i was having trouble starting till i did an extra ground cable and the starter upgrade.
busaboy may be right but it was easier for me to do the extra cable.
u seem to be right about everything but the starter is not a reduction starter. there are several starters that i looked at (from my junk yard friends) but had to buy the 17610
like you said 1.4kw is the way to go.