Ive got a 454mag w 350hrs and want a lot more out of it. Money is definately an issue. Reliability and fuel economy are important too. That all said, what is the best route for me?

There's no replacement for displacement, but building a 540 the right way will probably cost more than putting a SC on a 454. That being said, your 454 Mag will not have inconel exhaust valves, and that is pretty much a requirement for a reliable SC engine. At 350 hours, you are probably looking at a refresh to run the SC. A 540 might be the best way to go.

put some fresh valvesprings in it, bolt on a blower, and enjoy! To get similar power and torque from a 540 N/A, you'll need good heads, decent cam, new intake/carb, etc. Money wise, best bet in my opinion, do the blower. You'll be pleasantly surprised.

I had a buddy install a pair of whipples on 454 mags years ago. Engines had about 300 hours on them at the time. Ran great after the blower install for a long time.

If you go the blower route, which will work good, you definitely need to change the head gaskets to felpro or cometic. You will either by choice or at an inoportune time need to change them, and that's if it doesn't create other issues when it blows the stock head gaskets.

Reliability and fuel economy?

Seriously?

A 540 NA will likely give you a little better fuel economy since it isn't spinning the parasitic drag of a blower.
A 540 NA will likely give you better reliability if you run a mild cam and light valvesprings.

So the question is, what power are you seeking? If you want reliability and big power, you may be looking at a supercharger on a 540.

All of the combinations mentioned will give you the ability to produce a lot of power. Reliability, though, assumes milder cam profiles and easier work for the valvetrain. Most bigblock problems come from exhaust reversion, valvespring failure, lifter failure, detonation, and lean fuel mixture. Compression and boost lean towards detonation. Cam profiles and valvespring rates lean towards valvetrain problems.

You want to make big power on a budget, bolt on a blower and fool your motor into thinking it's bigger.

You want reliability? The devil is in the details...

MC

Also you might think about the pistons in the 454 I believe they are cast not forged and will need to be changed for the boost. They may not last long. Corrrect me if im wrong. Just my thought.

Since its a 454 "MAG" it will already have forged pistons

I have SC 502's, and I can tell you. About every 10 hours, you need to change the oil. The blower pushes gas past the rings and you get gas in your oil. Go with the 540. They make bigger blocks than a 540. You can get a 800hp engine that is not supercharged now days, but it will be bigger than a 540.

how much bost are you running on that motor? i have been kicking around the idea of a super charger for awhile now also. i have a 454 block that i was going to turn into a 496 and now i have been thinking i should go 540 instead but ta 496 with a low boost supercharger seems appealing.

540>454sc
There is no contest that the N/A motor is going to give you more reliability and the mpg is going to be similar. I think a supercharged 454 APPEARS cheaper because you aren't thinking of the little things. Cometic head gaskets, she'll need rings if not pistons, head rebuilds with at least better springs and really should have valves as well. Fuel pump, gauges, and a few other odds and ends. Now tally up selling your 454 and bolting in a 540, I bet the final cost is pretty similar