Contact Doug,he will give you good advice.I am sure that eventually you will get many recommendations here,but you have to realize that what sounds a certain way to someone,wont necessarilly sound the same to you.In order to find that tone you are looking for,you have to try a lot of different tubes.You say you are looking for "a more Marshall sound".To me that is kind of unrealistic,a Marshall is a Marshall,a Boogie is a Boogie.I am not saying it is impossible to get what you are after,it depends on "how much" of a Marshall sound you are after.It is all subjective.Better to ask Dougs advice,since he has likely tried all the tubes he sells and give you a better idea of what may work for you.The tubes you have in the amp right now are over 25 yrs old and you will undoubtedly see a big improvement in your tone with just about any fresh tubes.As for the caps,I can tell you in my experience that any caps that old need to be replaced,and have never had a customer not see an improvement with fresh caps.The filter caps are the large caps in your power supply that resemble batteries.As they age,they slowly deteriorate and dont give you a strong,tight power supply.This causes the response of the amp,particularly the bass response to get somewhat mushy,and not as tight sounding.The fact that you ask tells me it is best to have someone do it for you.
