The fastest, cheapest way is a set of Trick Flow 38cc street heads on a stock bottom end... periodfullstopdone13enginestoprooveit!
Do not touch the bottom end unless the cylinder walls are Really bad, they will work fine at speed.
As soon as you start cutting heads you are down the rabbit hole... Now the chains get sloppy and tear up the rails, custom tensioner pistons are going to be made $$, The front cover will need to be milled at the top, A pain to hold to cut right.
Going from 52cc to a 42cc is a big jump, look up my builds on welding head chambers, that is a lot of work and machine time $$
Then there is the why did you do this without doing that? You were there and said...
How will you know how it will run? They all come out different even when trying the same formula again..some start to detonate and you must pull timing and the power goes down fast and you wonder what changed?? It is fun and costs a lot but it is expensive and it has all been done on the 4.6, multiply 281 CID x 1.2 hp/cid and that's all you got when running NA.
I have gone as high as 14:1 with no problem and then had lower comp. engines give me fits and run fine at low timing and HP ?
Here is a big head scratcher for you to think about, raising the compression is not a linear scale, Just because you get 14.7 HP going from 8:1 to 9:1 you do not get the same jump going higher, 13 going to 14 is 5 HP. Higher compression can help a cam run better and make a small cam sound wicked, but much more heat and stress on all the parts and they do not last as long, look at this vid with little cams I made.
Loved that motor but blew a rod bearing racing a Porsche.
Call me, write me, throw a rock threw my window. High comp is not the be all end all like the old days of leaded gasoline. Running regular gas makes more power because it burns hotter and you can raise the timing more earlier. The biggest reason I can see to up the compression on a 4.6 is to get a big cam to run right and that is for drag racing and there are some good guys here in that direction.
I road race so I am looking for torque to dig out of a corner and out pull the Japs and Eurotrash.
Go look at the thread BLAK54 has going right now on head work..I can not think of 2 people, him and me that have done more silly shit building engines because we can with all the toy store tools you do not have. We don't care if they do not come out right we got the next idea churning in our heads.