Thanks for the great input from all of you as above............  
The shortcomings of the 4 speed were really
noticeable last Anzac weekend on the thousand KM return trip to Albury for our CAPRICIATION Celebrations
which was a real hoot!
Around town up to 80 kph it's acceptable with the 4 speed

Pm sent JR.

I think the rx7 5spd is just as good as any box , seen them behind some big turbo rotary cars and held up well . id like a rx8 5-6 spd  in mine if I get around to it ...

An alloy 6 speed behind my uprated V6 would be a dream made in heaven ! .........  drooling at the thought of cruising interstate in 6th with the revs around 1500-2000 ! 
Must drop my shaft and fit new UJ's ........  been on my mind since I heard someone (who shall remain nameless) lost his prop shaft last Anzac Day in his Capri .........  that experience would've done my head in big time  !
Don't even want to imagine the front yoke digging into the bitumen and flipping the car into the air !
Good reason to fit "protector strap" under prop !

BEE VEE
An alloy 6 speed behind my uprated V6 would be a dream made in heaven ! .........  drooling at the thought of cruising interstate in 6th with the revs around 1500-2000 ! 
Must drop my shaft and fit new UJ's ........  been on my mind since I heard someone (who shall remain nameless) lost his prop shaft last Anzac Day in his Capri .........  that experience would've done my head in big time  !
Don't even want to imagine the front yoke digging into the bitumen and flipping the car into the air !
Good reason to fit "protector strap" under prop !

yeah same here a 6spd would be just great imo   would sit well with highway driving  from memory its not that pricey as well , probably one of the cheaper routes to go  and stuff all mods needed from some of the uk reports
 

BEE VEE
 
Don't even want to imagine the front yoke digging into the bitumen and flipping the car into the air !
Good reason to fit "protector strap" under prop !

The 'mythbusters' couldn't get it affecting the car at all, until they had the front of the shaft going into a deep slot across the road. That lifted the rear wheels off the road momentarily. But it was a large car.

BEE VEE
 .........  drooling at the thought of cruising interstate in 6th with the revs around 1500-2000 ! 

But would the v6 be able to deliver the torque required at such low rpm?  It's cam profile and stroke wasn't designed for that rpm range.

I saw that clip on Mythbusters Noono. Such a huge yanktank; it surprised me it got as much lift as it did. Fully expected the diff and prop to come thru the boot lid !
 

GTV6

BEE VEE
 .........  drooling at the thought of cruising interstate in 6th with the revs around 1500-2000 ! 

But would the v6 be able to deliver the torque required at such low rpm?  It's cam profile and stroke wasn't designed for that rpm range.

Not sure with a stock oval port V6, but my D-port Special has unbelievable torque. How many Capri V6's out there can accelerate heavily from 40 kph to 100kph in top gear while continually climbing a very steep road ? 
I must look for the CAM measurements I took when I had the whole engine in pieces 3 years ago. It's def no stock cam.
But even a stock V6 dropped into overdrive at 100 kph should not be a problem I would have thought ?
So many guys have done this overdrive conversion before and I havent read one of their stories turning "sour".
Can anyone comment if theres ever been an issue with overdrive lack-of-torque on even a stock V6 ?

Oval and D port have the same torque and they all pull well from a crawl but can they sustain that much torque for long periods without over heating or excessive wear. Most 5speed conversions only drop the revs at 100k's by about 500rpm so Im not sure if it could handle a 6 speed.  Would be nice to know.

Yes. It’s a valid point you raise.
Hoping to hear from others who can share their opinions.
But when I think of the buz box rice burners that have miles less torque than our Essex V6’s that have o drive with no issues, it makes me wonder.
Like them, we have the advantage of power to weight with Capris light body.