Camshaft removel.

[muncher]

Hi Everyone. Been a while since I was last on here. I had a 289 mustang that I finished and sold over winter here. Now I am turning my attention to by GMC Steppy. It has a 305 V8 that runs great but could do with a boost in power. I also need to replace the valve guide seals. So I thought whilst I am doing that I could drop in a performance cam and lifters. Some details on the engine.

Fuel injected with original hedders.
Vortex heads.

Can I remove the cam without dropping the sump and removing the front engine cover?
Also what cam could you recommend. Interested in low down punch rather than top end.
Would also like to upgrade the headers.

Any advice/tips/hints I would really appreciate.

Cheers Guys.