Yes but people swap the better 350 balancer and bottom pulley in place of the 305 one all the time.

Bore is the same on 305 and 350, the difference was in stroke. 283 and smaller had 3.875 bore, 302-350 had 4.00 bore, the 400sbc had a 4.125.

Only real way to size a engine is to pull the casting number off the ledge on top behind the drivers side head.



Don't worry about the vin number spot. You aint trying to number match it and that's stamped in. Often milled off or tampered with. The number cast in is harder to mess with.

The head numbers are under the valve covers

 

the difference between the two is The 305 has a 3.740 bore and a 3.48 stroke.
The 350 has 4.000 bore 3.48 stroke
The bore and stroke of a 4.3 is the same of a 350, only with 2 less cylinders,

 

It’s nice to have the vehicle like this; I not heard much about it but searched for it on Google & got lots of stuff related to it.