Cooler intake manifold

I was thinking about using exhaust heat crossover block off plate's and a lifter valley baffle, insulate the bottom of the intake manifold. The car will not be driven in the winter time. I've read that a cooler a/f mixture is good for power, is this true?
It is true. The above ideas are a good start.
The lifter valley oil plate keeps the hot oil off the intake. That’s a plus 1.
The exhaust cross over blocked is a big one and that’s plus 2. Keep adding!

Also would a carb spacer be beneficial, if so, how tall and what would be the best material for it to be made from?
Brook James nailed the material to use for keeping things cool. The height of the spacer can be an issue to the engines performance. This is more important than keep the carb/fuel cool. In order to keep the carb cool rod best performance, you would have to stick it above the hood in full to catch 100% of the moving outside air.

To this end, without dyno testing or track testing, I suggest (slightly blindly mind you) that a 4 hole spacer (a known torque provider) as high as the hood allows.

Best place to locate the air pick up for a cold air kit, and is there a kit available to insulate the duct work for the cold air kit?
Try a search on a “Ram Air Box” air cleaner. There are air cleaners kits that have a single or dual (mostly seen) snorkel and ductwork that allows the air entrance to be placed advantageously where you need or want it.

OE equipment that use ductwork for the air cleaners tended to route the duct to behind the headlight, drivers side. Look for a picture of a Cordoba.

Are K&N air filters the best for a filter. I have to find ways to improve performance without breaking the bank account.
I have seen test where a paper filter out flowing a K&N only when new with the efficiency dropping off rapidly as the filter gets dirty. I use K&N filters. There worth the expense.

The cool cam mention is a good one. However! Keeping the cam cool at all times with ice is a needless PIA. I rather suggest wrapping the fuel lines with insulation even though it isn’t a pretty sight. It is very effective.
Also, make use of a return line for the fuel. The constant introduction of cool fuel from the tank is a big plus and the (slightly) heated fuel will not increase the temp in the gas tank. The heated fuel from the return line will dissipate it’s heat Immediately and effectively.

The sealed from the heat and open to cool air idea above is also really good. That’s if your carb is going that high and can be easily sealed to the hood with fresh air available to it.

Run a colder thermostat.