From what I have seen.
Cav is very well built and probably the most streetable/comfortable.
RCR is probably going to perform best of them all on track.
Baily probably good on track, but crude.
The above 3 are cars that look like Gt40s, but are somethign different dynamicaly.
ERa always built a great product and its pretty close tub wise to origionals.
An SPF there may be minor trim detail differences to a 60s Gt40(guage size, door latches etc) but the tub and suspension layout are the same, they even copied the shitty open bearings. 60s brakes sucked as did tires, so more modern brakes and tires are not a sin even for historic racers of origionals.
SPF also makes a rhd sill shift for the asking.
Basicaly if you want to drive a 60's Gt40 on sane budget the spf or gelescoe is the way to go. Does a spf use different fuel pumps and aluminum uprights plus other bits, yes. But the drive feel and dynamics are the same. Thats why its best termed an authorised continuation.
I had historic racers literaly drooling over mine. I am talkign people who regularily drive "origionals" T70s, ferrari GtOs etc.
If you want to drive a car that looks like a Gt40 and is maybe somewhat similar in feel then the others may be a great and better choice.
As always build quality, as in the bits used in completion are key.
I went spf because to me an authetic GT40 driving experience/challenge was important. Cant afford a so called origional(you know they have all been retubbed and new bodywork) so a SPF looked to be a 9.8 million dollar discount for the same car dynamicaly and stylisticaly, just sans data plate. Yeah maybe the ignition key is different, but the differences on a spf are trim detail differences not fundemental execution.
In a spf when you are out on track the skill needed to go certain speeds, the feel feedback etc, thats the same as the greats experienced in the 60s. Well yes slightly less skill needed now because the cars have more power, better brakes and vastly better tires, but thats true of any historic racer.
at 2463 lbs with full gas, 580 hp and running hoosier historic race tires there is not much that rolls up to my local track that will beat it. Well porche 918 will, and a Gt3 depending on track, because of the pdk. A new zo6 vette on the street pilot cups will not out handle a spf and will wilt on a hot day after too few laps.
Performance is relative, and moderns make performance extraction easy if purely chasing laptime numbers is your thing. But as Dennis O has run right on 2 mins around the glenn, look and see how many moderns if any can run that time.
If I wanted a "real" Cobra it would be a Kirkham, because its so close as to be the same. I would say the same about a SPF.
Depends what you want the car for. If you just want to cruise around, or chase ultimate laptimes there are probably better and less expensive options for either of those priorities. Course you could put an alumninum 427 in a spf and blow somehtign else away.
How far do you want to stray from what was built in the 60s.
There is a reason mine is rhd(tracks are mostlyt clockwise and rods shift way better than cables) 302 carbed. Yes a 302 is not a 289 but the functional differences from a driving perspective are irrelevant.
My only mistake was getting the ac, never used it. But maybe one day it will become a sort of street car so the ac will be good..
Speaking of which, maybe mine is setup for track, but a Gt40 seems pretty far from a street car even if street legal. These cars are noisy, hot hyper reacative, hard to see out of all around and maybe a bit much for street use, unless maybe you live somewhere with big open roads or are used to a lamborghini miura, and even then...lets just say that something like a ferrari BBi or lotus elise is a paragon of virtue as a street car compared to a Gt40.
They are all cool cars. Whats better for your purpose and budget.