I am looking at the same question since I am planning a 5 speed swap.
I need to preface my opinion with the fact I am basically cheap and would rather build than buy. That said we built a new z-bar for one of the racecars last winter and it performed flawlessly. That makes me think mechanical linkage because it is always simpler and more reliable. I have thought about the external hydraulic linkage that uses the stock cable fork.
Kinda on the fence yet but leaning toward the z-bar.
Low buck, touring style, '73 Convertible "rolling restoration", 351c, 2v heads with a shave and a haircut, Performer intake, Holley 650(ish), roller rockers, screw in studs, guideplates, stainless valves, Duraspark / Motorsports MSD, T-5 conversion. 1-1/8" front, 3/4" rear swaybars KYB shocks and some home brewed subframe connectors. Future plans; JGC steering box, Cobra brakes and... paint, interior, etc.
When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passenger.
You MAY have a problem with the long tube headers and the Z bar, since you have spent the money to have the headers coated. The use of the bar may necessitate some "banging" on the pipes which will surely not be GOOD for the coating on the headers.
I think I would go with the hydraulic clutch in this situation.
Do the RIGHT thing.
I am in the middle of reassembling my car and also would like to head this one off while the car is dissassembled. I have searched quite a bit and not found much, but I would like to share with others what I have found.
The biggest problem I see is mounting the clutch master, brake booster is in the way big time. I personnally would like to use an external slave, but if the headers end up hitting, internal slaves are avalable for the top-loader.
I have seen the hydraulic clutch done 2 ways in a 71-73. The first is by buidling a master cylinder mount that is right behind the P/S gearbox. Kinda hard to describe, pictures worth a thousand words so search for "hydraulic clutch 73 convertible" on the "Ford Muscle" website. That is a 5-speed conversion.
The other way I have seen it done is by making a bracket that attaches to the clutch pedal. From the drivers seat it is bent to the left. The clutch master is mounted to the firewall just to the left of the brakebooster. It is a tight fit, but it should work. The pushrod attaches to the "L" bracket. Should be able to find this one on the internet as well, I run across it occasionally.
American Powertrain does list a hydraulic conversion kit for 71-73 Mustangs. I did talk to them last year, I think, and a bracket has to be fabricated that bolts to the clutch pedal. When I talked to them about it they were looking at having that piece supplied to make it a complete kit, haven't heard and haven't had time to check. It is kinda pricey. I requested the instruction sheet to see how it installs, they wouldn't send it to me. I would like to see how they mount the master cylinder.
That's my 2 cents.
same coated headers in the way scene[71 460 toploader] we purchased the powermax setup and are stumped on install. firewall w/ large booster in the way and pedal doesnt have a hole, but a pin. z bar to pedal rod pulls up thru floor 1.5" when pedal is depressed. the master cyl. would have to move up & down with pushrod pushing on floor to work. we would rather mount it verticaly down where z bar mounted. is it possible?
I have recently sucessfully completed a 460 toploader installation. I would recommend the mechanical OEM type linkage do to the ease of installation with less problems. I also had to install the pedal set & z-bar in my car. I used 85 460 P/U truck exhaust manifolds and modified a H-pipe to fit. I would suggest to obtain a OEM Z-bar (302 & 351C type) and remove the lower arm. I fabricated a new arm and then had the ability to relocate or bend it to clear the exhaust as necessary and them weld it together. It all went together and works well.
Just my .02, I converted my '68 coupe J code to a 393w and a Tremec TKO-600 with a clutch cable kit from Modern Driveline. It was fairly easy and it worked well with my mid-length headers.