How much does it cost to engineer a 1600 to a v6 or 302 v8?

Like whools said How long is a piece of string?/ lol
Your "good front end " wont be any good for a v6 or v8 conversion that would have to beefed up as well.
Id check your local RTA , I have heard somewhere that they are not passing these such conversions and varies from state to state.
You will have to spend some time researching it. That is why the cars with the v8's already engineered might be a better option in the long run..
My 2 cents anyway . Have fun

Thanks for the info guys, really appreciate it.
 
Are they even that strict on a v6 essex/cologne conversion though?!

The V6 and 4cyl shells are different strength-wise in the front - those in the know will know of what I speak. e.g. whooliigan
The V6 Capri also weighed 1080kg new, the 4cyls <1000kg.  Some states have/had permissable max engine size upgrade based on original weight of vehicle. The Essex V6 is 183kg alone, and I'm led to believe to 16oo Kent is about half that, with Pinto 2lt somewhere in between.
If you can actually legally go V8 route, then you will need a chassis strengthening kit for starters, then  $$$running gear, $$$brakes etc.
If you do, pls sacrifice a 4cyl shell and not a V6.
 
Heresy part - what about a TC/TD Te/Tf Cortina 6cyl donor car for your V8 project ?
 

Im doing one at the mo - but the new regs from vic roads only allow for an engine size 4 times the tare weight of the car - so for a m 1 v6 shell (1057G) - the max engine sze would be 4228 cc.
 Which would eliminate a 302 windsor. I had to get a 2.8i shell - 1230g tare - so 4920cc - which is allowable. But u need a pollution set up to comply. In addition, they require a max 800kg load over the front wheels in this applcation.
 
u would also need: 5 stud rims, upgraded brakes, bronco sump, and hadfield kit (or similar). My donor car is an 89 model falcon (fuel injected). Engineer - depends on how switched on u r - if u get it ALL  together - maybe under 1k. (youll have to pay for a brake test)