I got a deal on a TF Score that came with a .46 LA installed. It flew OK but seemed to struggle a bit on the vertical up of the square loop, and slowed down at the top of a wingover.

I've seen a lot of post on ST.51 and various 4 stroke power for this plane.
I thought I had a ST .51, but I just pulled it out of the plane it was in and it is a  V.56. older version, baffle piston w/ 1 intake port, ringed piston, ball bearing rear and 1 hole in the middle of the exhaust for muffler mount screw. Crank is marked BB56 on counterweight, and " CHROMED" is cast into the case below the mounting lug.



The engine is an R/C version, but I have a venturi for it somewhere.
Anyone have experience with this combo, or the .56 R/C running C/L venturi in general?
 

Since you have the ST .56 its certainly worth a try. If its a strong one and the Score weights around 75 oz. or less, the 56 should fly it, probably with more authority then the LA .46. I tried one in mine and it did OK, but later I switched to a "dish head" ST .60 and it flies much better, especially in a moderate breeze.

My Score weights 80 ounces and it really needs a strong engine. A .65 would not be too much! Another local flier tried a Tom Lay ST .56 in his 90 oz. Strega. It was not enough, even though the engine ran well. He also switched to the ST .60.

The nice thing about these 2 engines is they are pretty much interchangeable in the same model without reworking the nose. One drawback to the .56 is I have never seen one with muffler mount ears on the case, so a strap-on is needed. Installing one can be frustrating in a cowled-in stunter.  EWP

The plane I took the .56 out of had an adj. motor mount ( R/C ARF P-51), and I had to widen the spacing when I put a "G" Series Blue Head ST .60  in it.

I think the G .60 is heavier than the V .56, there is certainly more meat in the case around the cylinder for the muffler ears.  I thought about putting the 60 in the Score, but it is wider than the .56 across the beams, and the .56 is wider than the LA .46, so some surgery would be necessary. Also I suppose the G .60 would need to be re-worked for C/L Stunt......

The .56 is in the crockpot getting cleaned up now, liner / piston / rod look good, rear bearing was covered in castor goo, so I'll have to see how it looks cleaned up. probably just order a new set of bearings and be done with it.

Oh yeah- I  can't find a venturi for it in the boxes of "Stuff"- anybody have one with correct needle valve assy they want to part with?

+1 on Steve's comments about the control system; don't just think about it, do it!!

I replaced every thing except the horns; then the elevator horn arm turned on the wire shaft.  Fortunately, I was able to run out the tank and land with no other damage...........

If you have not yet acquired them, check out the used but good venturi and NVA I just listed on eBay (item # 300447327402). Best regards, EWP