So the O.P. has a '63 dart and wants to put a V8 in it , well it can be done after the firewall and windshield wiper motor and linkages are changed to '64 -'66 then there will be room for the distributor to clear the firewall without the cap being broken .
Don't even think of taking a hammer to the firewall to get clearance it will mess up the wiper system .
So for a guy that doesn't have a bunch of time this should discourage one from doing a V8 swap in a '63 not to mention the cost . Of course the added expense of adding disk brakes , wheels and tires and headers and complete exhaust system , radiator , hoses , conversion engine mounts , V8 torsion bars , V8 center link , etc. etc. etc. $$$$
Here is a picture of a V8 on its new mounts sitting in a '63 notice how the wiper motor bulge leaves no room .
Remember it wasn't until '64 that the A bodies got the V8 and a new firewall and wiper system to make room for the V8 , this set up ran through '66 .
This is a picture of the inside of the '64-'66 firewall and wiper mount note the bump on the center of the firewall this gives the Distributor the clearance .
Here's a pic of the engine side of the '64 -'66 firewall , see the divot next the the wire .
View attachment 1716213088
View attachment 1716213089
View attachment 1716213090