1) There is a Kaiser connection because GM sold the engine and machine tools to Kaiser Jeep. Kaiser used this engine in the 67 and later C101/Commando. When AMC bought out Kaiser Jeep, they wanted to use their own engines, specifically the 232/258 6 cylinder. So they lengthened the vehicle, gave it ugly boxy front sheet metal and it became the C104/AMC Commando. GM got in a bind because they had too many 400+ c.i. V8s when the 1973 Arab Oil Embargo occurred, so GM President Ed Cole (of SBC fame) drove to Kenosha from Detroit in a Buick Special fitted with an old Buick V6 to personally negotiate the repurchase of the engine.
I do have a 68 Commando and I like to tell people it has a Kaiser engine, not a purchased GM engine.
Strangely enough the V6 Commandos had a Turbo 400 automatic as an option.
2) The 700R4 was a Chevy manufactured trans and was used behind SBC engines. I have not seen one with a Chevy/BOP dual bellhousing bolt pattern. The 200R4 was a Buick manufactured trans and does exist in dual bellhousing bolt pattern versions. It is slightly smaller physically and hot rodders claim it might be more durable than the 700R4. There are sheetmetal adapters to use Chevy trans on BOP engines and vise versa, but it is probably better just to use a 200R4 on a Buick V6.