2003 5.4 to 6.2 swap
 

I have a 2003 f250 with 175,000 miles on it and the exhaust manifolds are leaking and spark plugs need to be changed. When I asked the previous owner the last time he changed the plugs he replied that he had never changed them and has owned the truck since 2006. This engine is very weak and if I want 400 horsepower then it means a lot of money and premium fuel whereas the 6.2 has 411 hp and 435 lb-ft with similar fuel economy and regular unleaded. If I have to pull the heads and don't like what I see how difficult would the swap be like what do the engines share. Also if everything looks good is there anything I should replace to keep it going like the timing chains and any cheap tricks to get about 50 more horsepower everything I have read is several grand to get almost nothing from it which is why I thought about an engine swap. Thanks for all info I have been reading for months on getting more power from this thing and if I'm gonna pull with it I don't want to lose what little low end it has to 4 valve heads it already spends a lot of time over 4000 rpms and losing speed on small hills with my 12000 lb trailer behind it

This has been discussed on other sites but mostly people saying dont do it but nobody saying why. Apparently unless I want to loose what little bottom end I have I have to supercharge my 5.4 to get anything out of it. So any help or anyone that knows anything unfortunately the ford techs I have spoke to are apparently only good for replacing broken parts.