How many old Mopars have you owned? and how many of those were NOT 318s?
The bores range from 3.91 to 4.04, a range of 3.3%
The strokes range from 3.315 to 3.58 a range of 8%.
the sizes have a range of 13.2%
For your application;
Case closed.
On the street, with an A-body;
you do not need 2.02s
you do not need a long stroke
You do not need forged parts
Any top end will fit on any bottom end.
Allowing for cylinder-pressure adjustments;
A 318 with a cam one size bigger than a 340, will match it for power.
A 318 with max compression will match the bottom end of a stock 360.
A lo-compression 340 with a 318 cam will about match the 318 for fuel economy but have more bottom end.
The 340 burble was more from the rectangular tips and high-energy exhaust. The 44* of overlap is actually very modest. For the street, I don't think much of the 340 cam and I have several of them packed away.
A 318 will happily rev to whatever a 340 can, and so will a 360. All any of them need is the right springs and lifters. KB107 pistons for the 360 are about 2/3rd the weight of the 340 forged slugs. After balancing, the 360 crank will go to 7200 as often as you like for more than 125,000 miles (mine)
A 360 can happily pull 65=1600 rpm (mine) all day every day. Try that with your 340.
What the 360 can do with a 3-gear manual, a 340 will need 4 gears, and the 318 will like 5
If a city car; the rear gears will need to be a least 10% greater between each engine. What the 360 can do with 2.94s, the 340 will need 3.23s and the 318 needs 3.55s.. As the engines get smaller, Second gear becomes very important, so that you always have the right amount of torque on tap.
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From Experience, I can tell you that having 400 ftlbs on tap at 45 mph is seriously big fun, but 400 ftlbs at 90 mph is nothing to write home about and 400 at zero-mph is absolutely bonkers
You cannot get 400 out of a streetable normally aspirated 318
