I swapped a 360 into my slant six dart and now the throttle is super heavy and kinda sticky returning to idle (pretty much the only reason i wont drive it right now) and when i give it a bit of gas it doesnt want to return to idle without me pushing on the carb linkage manually... i have dual return springs on the carb, so i dont think thats the issue... could it be because im using a slant six throttle cable on a v-8? it does kinda have to bend around a bit...

Yes, You ahould replace the /6 throttle cable for a V-8 throttle cable which is a good bit shorter.

Hopefully replacing the throttle cable takes care of your problem.

I had the exact problem with my truck but it was the original cable.

After a killer set of return springs I resorted to returning the carb to Holley.
Removing the throttle cable, inspecting and lubricating it. It felt 100% ok on the bench. Relocating my throttle spring bracket.
Lubricating the accelerator pedal.

Finally I replaced the throttle cable and it feels like new.

I had one that started to unraval in the plastic sleeve and hang up going back to idle

I put heavy springs on it to help,then one day in traffic the cable broke and had no throttle

got to a store and cut a string off a tree that had just been planted and tied off,used the string from carb through firewall and pulled by hand

FYI
some of the v-8 trucks have a throttle cable that will work on an a-body also

fixed 2 on my 68 Dart that way

If you have trouble locating a new cable, this place makes a nice product - though a bit expensive:

Imperial Services

I would pull the cable and make sure it moves freely and check out the linkage to make sure nothing is binding, if the cable is bad I'd go for the shorter V8 version.

I've also seen where if you throw 2 heavy springs on 1 side of the throttle lever it can distort the shaft enough to bind up the throttle blades, you can rework it with 2 lighter springs, one forward and one back off opposite sides of the lever and still have the safety of 2 springs.