Have you thought about having it recored I did my 47 radiator a couple of years ago-people that do truck radiators might be able to do it. Not cheap 1-2 k

I think you are better off with a single lead acid battery-than 2 optima in parallel-Also if you insist on using the 2 batteries in parallel-they need to be purchased together to try and get internal resistance as close as possible to each other . Reason is in recharging if not equal one battery will get more charge than the other.

for what it is worth-blower motor in my 47 Super Clipper quit working-it is underseat unit-but mtr is probably same or close to what you have. I got the motor apart and for some reason varnish or something had locked the rotor and stator. Cleaned them up and now works. I suspect the motor was subjected to a low voltage due to additional resistance on connection points. By the way the motor split in middle-careful with the brushs.

check ebay-that stuff comes up from time to time

If you have not tried it-there is a small hole in the shifter column about 1/3 way up from bottom. Squirt some oil not wd40 into the hole-work the shift lever and/or let it sit over night. I was able to free mine up. It happened as recently as about 2 weeks ago. Good luck

Easy enough to check-when you shut it down disconnect the battery-next time you drive it-if starts ok you probably have a short somewhere that is draining the battery. Also when running check the battery voltage at the battery should read 6.5 or more if generator/voltage relay is working.

could be a weak coil-did you try starting fluid in carb?

If vapor lock-the normal fix is a electric fuel pump

I just replaced my battery-lasted 3 yrs but had a problem with the Voltage regulator that may have shortened the life. I usually get around 6yrs-use batteries from tractor supply

ebay listing for mounting bracket-372896661196

coils do not get better with age-The coil for this car with the connection on the back end is hard to find and expensive and prone for trouble because of age. I purchased a generic 6 volt coil-found a bracket on ebay to allow it to mount to firewall-ran a wire from the front of the coil along side the coil to the connection point in the firewall-not orginal but it works and has for about 10yrs.