replacing fuel pump / timing chain

[1970911T]

I need to change my fuel pump on my 1968 911L that has weber 40 ida's. The pressure seems to be all over the place. There is a Hardi pump, a "Pierburg, Universal " and a "Rotary Fuel Pump, 12v" listed on the Pelican site. I am not too concerned about price but I want to have a pump that works well. Does anyone have any experience with these pumps or any others? Where is the best place to install the pump? It is currently in the engine bay. Should it be mounted near the gas tank?
Also, I think I should replace the timing chain and the mechanical tensioners. I am not planning the hydraulic tensioner upgrade at least not yet. Can I do this without removing the engine? There is a tech article on how to do it without splitting the case but doesn't say if it can be done without removing the engine.