Thinking outside of the box, I would say eco boost 4 banger from the new Mustangs. Power, economy, and light weight.
That is great $$ per HP! IMO the Boss 9 is a neat looking engine, but I think you could build an 600" engine with P51 or A460 heads that would make the same power for less $$$. The Boss has the advantage of letting one run a hydraulic roller, which would be better in a street application.
One day I want to build a clevor w/ either Brodix BF202s or the CHIs that are out now,but the little 395 ci mtr I am working on now will have to suffice.
Ron Pond all aluminum, stroked 427 FE... No it would not be going in the Comet... http://www.robertpondmotorsports.com/427-ford-engine-block.htm
A year ago, I would have said a 426 hemi with a 6 or 8-71 sticking out the hood. But now I am thinking more of a twin-turbo diesel would be more cool. I drove my boss' twin-turbo BMW 355d and it was quick! Then I bought my wife a Jeep Grand Cherokee with a tiny 3.0 V6 turbodiesel, and not really quick, but fun for a big heavy car. Hauls a boat like it isn't even back there. Something like the one in the BMW would make the Maverick a FUN car with good gas mileage. Maybe even something a little bigger. Video from Facebook, so you may not be able to see it without a Facebook account. https://www.facebook.com/video.php?v=10154498445885112
I like a high winding NA peanut engine like a 302,289 or 283. Regardless of manufacturer, they are fun to race, watch and hear! My 306 isn't built like these engines, but one can dream. If I had one of these in my Comet right now, I'd probably only break things. To see and hear what I mean, this first video is an in-car of a Fox Mustang and 306. This video is a SS/K event at National Trail Raceway here in Ohio. According to a guy I know that races a Chevy Nova in this class, these are all NA 283 cars and one lonely 289 Mustang. He further states all the 283s must utilize factory heads, all 289s are allowed aftermarket heads due to a rule modification finagled by Carol Shelby many years ago.
If I build another engine for my car it will be a 460ci small block out of a Winsor dart block but will be a long time before my 306 gives out I hope
Been thinking of building a 532 big block but the again I'm pretty happy with the 418 and like Ray said its pretty cheap to build the SB and make good HP.
I think probably the Coyote ford would be the cheapest big Hp mtr to run now.Just put a procharger on it & tune it & you are set because it would not require any internal mods,these are beefy engines internally.They claim out of the box you can turn a 1000HP.
Those modulars can produce some sick HP numbers. Wish it didn't require so much surgery to fit one in.
While they're certainly nice.. I sure wouldn't call them the cheapest. Easy to make bigger power?.. you bet! For that same 10 grand on the base motor.. you could also build an AFR headed Dart block and toss a blow through setup that will still make comparable power. Sure more setup and mechanic'an to do from the ground up.. but I see more and more huge power adder setups on the traditional stuff too. Tons of stock block stuff running around with bigger power adders. I also see 600+ horse stock block Fords still running around on hypereutectic pistons and borrowed time every year too. Tuning is key but still crazy stuff and only a matter of time before they eventually drive over their oil pan.
Ok.. I'm in gear-head mode lately so I'll jump in now too. Aluminum Man-o-War 8.2 deck block with Kasse P-38 heads. Home crafted equal length IR manifold made of carbon fiber with ITB/EFI. 4.125" bore x 2.85" stroke with short ultra-light custom pistons, 5.7" ultra-light Chevy rods, knife-edged/fully polished crankshaft with Honda sized journals, with just about every high-performance coating known to man used inside it. 575 horsepower @ 7,800 rpm plus 6 speed in 2,500 lb car = too much fun. High 10's and still able to hit 170+. My personal version of a Comet GT supercar.