Here is my input on your options. I am biased towards the 292 in the Chevy II as a small block in Chevy II is boring....
A thin air cleaner will work on a Chevy II with a 292. On my 66 I ran an Edelbrock carb and no spacer on a Clifford with the 4 barrel adapter. An Offy would likely work a little better clearance wise.
Notice on the engine mount you pictured, there is no provision for a mechanical fuel pump. You can either go to an electric pump or use a stock right mount with the top bolt hole elongated and weld a new "tab" on the subframe to use the stock pieces.
The stock 63 radiator should be ok if you do not get stuck in traffic on a super hot day. I believe the 65-67 6 cyl radiator is a little wider; you can probably get someone to donate one.It will allow a little more water capacity. As far as the fan, each combination is different; worse case you can go with an electric. I have a custom two core that we had built since the fan went into the stock radiator on my 66. It gave enough room for the fan and clearance with a fluid dampner.You can have it for the cost of shipping if you want it.
If you want easy and have the money for the kit, putting a 350 in the Chevy II will take no fabrication and the truck will be a drop in. If you want something you will not see at every show or dragstrip and are not opposed to doing a little welding, go for the 292 in the car.
