Greetings!
Being that you plan to use this as a daily driver, and not for racing, I see no need to use anything other than a stock set of heads. I know there are quite a few opinions re: which head to use re: open chamber and closed chamber. Either will work fine for routine street driving, but a lower compression set of heads will allow you to run with a lower octane fuel. In our case for our 69 Shelby GT500 and our two 73 Mustangs, we use non-0ethanol gasoline, as I prefer to not have to deal with ethanol fuel that coagulates in time, and to avoid any long term issues with alcohol on the fuel system components that were never designed to be exposed to alcohol, even if it is "only" a 10% mix. The good news is we still have non-ethanol gasoline available., The bad news is that is cost more than even premium ethanol mixtures of gasoline, and it is only 89-90 octane. So, no getting aggressive with ignition timing and compression ratios for us.
I am glad to see you have an eye on longevity. In a prior comment Ron Tanzi suggests having the valve guides getting bronze walled, and I totally agree. Another great move it so replace the oem style umbrella oil "seals" (actually oil splash diverters) with a "real seal" design like Perfect Circle offers.
Another thing to do is to install hardened steel valve seats.
As for the use of flat tappet cam and lifters, I have seen a lot of posts re: folks who have flat tappet cams and lifters that are getting wiped out very quickly, despite them using proper cam/lifter break-in lubrication and engine oil with Zinc in it. The speculation is they are either not following proper break-in procedures and/or incorrect lubricant (I doubt that is the case for experienced engine builders), or the metal used for the cam lobes and lifters is not hardened properly. With the report of ever more use of Chinese parts being used I suspect it is more a metallurgy related issue folks are running into. For myself, I have pretty much decided to invest a bit more in any new valve train parts and go with a hydraulic roller can and lifter assembly, just to avoid the issues folks are running into with failed cams and lifters. For me, it is a matter of doing what I can to avoid having to tear an engine down a 2nd time in the event of a failure of the cam lobes or lifters.
Along similar lines, in the event you opt to use the old school flat tappet cam and lifters, I would be the last person to throw a rock at you. But, please be aware most modern engine oil does not contain (enough) Zinc to prevent premature or rapid wearing of flat tappet surfaces. The reason they have begun to not use Zinc any longer is because Zinc impedes catalytic converters from working properly. These older engines do not come with catalytic converter exhaust parts, so no need to avoid Zinc. More important, Zinc is needed to help lubricate high spring pressure designed flat tappet wear surfaces. If you engine oil does not have Zinc, you need to use a Zinc additive if you have a flat tappet engine design. Or, better yet, use an engine oil that already has Zinc in it. I use AmsOil Z-Rod 10/30 (it comes in other weights also). If your engine oil does not clearly stare it has Zinc in it, and you are running a flat tappet engine, you need to change oils or start using a Zinc additive.
Finally, when it comes to timing chains and gears, I prefer to use a double roller chain and gear design. And, I will not use gears that have a plastic or nylon tooth assembly. An all metal set of gears will be a bit noisy compared to gears that have a plastic or nylon coated set of teeth, but the all metal design will last far longer.
Okay, those are my thoughts for what it is worth. Have fun with your Mustang!
