Yes there are pros and cons to v8 over inline 6
The main con of the v8 is the exhaust and steering
And it burns more gas.
Pros are more power, shorter so more room for cooling system and such.
It just might win out over the six when paired with the 4L60e
Cheap
And it’s been done by others many times.

With a manual transmission the 250 is a no brainer for me.
Not so sure with the 4L60e,
I think the sweet spot is some where around 300ci
292 might be that.

It’s a pick your devil too fat or too long.
Fuel economy well you pick that up with the right differential ratio
Get it loafing along at about 70 mph.

One problem I thought of an elegant solution to is the shifter
Use a push button on the dash like Grandma’s old Dodge Dart used
Grandpa liked Dodge