In fact, "Marc S" on this board went the pushrod route with a Nascar motor. Hit him up and see if he'll tell you how much money the whole project cost. That should give you an idea.
My 734whp 284ci pump gas Mod motor with the super charger and fuel system cost me roughly $12,000. New, the Roush Yates 358ci 817 naturally aspirated sbf NASCAR Cup engine that's in my car costs $60,000. I Bought mine used from Yates and freshened it. The parts in these engines are very expensive and would be overkill for street use or even drag race use. So it's not a fair comparison of cost. The Mod motors certainly can make big power with a power adder. But in NA form, they can't compare to a larger displacement engine. The Mod Motors make great hp per cubic inch in NA form. But as we know, they suffer from displacement. However, HP wins races not HP per cubic inch. But all things being equal, if you took a Mod Motor with the same cylinder head flow, compression, camshaft etc, the engine with the most displacement would make more power. If I just had a bare S197 chassis and wanted to build a 1000whp engine for drag racing that had mild street manners and I didn't care about gas mileage, it would be a 600+ NA BBF. If mileage was a little bit of a concern, I could take my 358, lower the compression, install a much milder camshaft, and then put twin turbos on it. With a Fast fuel injection, I bet it would get close to 20 mpg on the highway and make north of 1200whp on pump gas.
As I noted, my 358 in NA form makes 817 hp and I shift it at 8800 rpms. Even though it has 11.96:1 compression, I bet I could run it on pump gas because the Yates chamber is very efficient and the camshaft is .803 lift and the duration is 280 @ .050. Even though it idles at 2400 RPMs, the engine is very drivable. It idles at 13.8-14.0 A/F and the A/F at a steady 3,500 RPMs is 14.4. That's the beauty of custom $1,000 carburetors. The only thing that makes my car unbearable on the street is the un-sprung triple disc clutch. That being said, the fuel economy during normal driving couldn't be very good. However, even though the 358 makes roughly the same power as my supercharged 4.6 did, it uses 1/3 less fuel while racing. With the 4.6, I had to fill my gas tank 3 times a day. With the 358, I fill it in the morning and I still have over a 1/4 of a tank at the end of the day. Why is this? Well, NASCAR spends a lot of R&D on fuel economy. That, and the 4.6 at full throttle was tuned for 11.5 A/F and the 358 is at 12.8.
I'm glad that I made the move to a pushrod platform because the Mod motor didn't work for the application that my car lives in. That environment is 99.999999% road racing and endurance events and .000001% street car.
Even though I achieved the goals that I set for myself with the 4.6 and I really like the Mod platform and the direction that Ford had taken it, I never got excited about it when I opened the hood. But that has nothing to do with the Mod motor. I think all fuel injected engines are ugly. But hey, I'm an old pushrod carb guy anyway and the fuel injection that I like tuning is a mechanically injected Enderle setup on top of a 1471 roots blower.
Don't get me wrong, I love my new Focus and it's modern fuel injection. For a daily driver, it's the way to go. for a race car, it's not my thing.
Hell, if the OP wants to put a 1951 ford Flathead in his car who cares. But when people question his decisions, don't take it personal. I have had plenty of people criticize my car and I could careless. It's my car and I built it my way. It's not for everybody and that's ok because I built it for me.
What's my point to all of this? I'm not really sure other that I have over 100K in my car including what I paid for it new. This year, my sponsors have invested roughly 20K. Having a dream and wanting to be different has it's price and the cost always exceeds the expectations. OP, be prepared to spend a lot more than you forecast to spend.