Im running a 327 with a holley truck advenger in my toyota landcruiser. Im looking to use a fuel tank from a 94 S10 blazer. My question, is there a way I can bypass the mechanical fuel pump and use the in fuel pump in the tank or use a inline fuel pump?

Sure, you can pull the mechanical pump and actuator rod and install a block-off plate. Generally, you can use an electric fuel pump. If the donor 94 S10 was fuel injected, its in-tank pump will be putting out much higher fuel pressure than your TA can handle, so you will need to have a fuel pressure regulator that gets you down around 6 PSI. If you choose to wire in an aftermarket electric pump, you have several low pressure options to choose from. I've had very good luck with Walbro -
http://www.walbro.com/

but Summit Racing is a good place to go to see your options