Of the ARF Cubs I have seen, the H-9 looks the best, in terms of covering quality and how well it is put together. I don't particularly like the wooden engine mount, but that can be changed. I have the 80" Ultra Cub, I think it is a discontinued model, not sure, but I bought it at a shop that was clearing out its ARF and engine inventory a while back. I'm about 1/2 through putting it together, going to put floats on it (Great Planes kit .40 size), going to power it with a .72 Saito. The instructions with this plane show a .50 Saito, and say it is a "perfect match"; Saito doesn't make the .50 any more, so I don't know how old this design is, but for an ARF is pretty nice. I imagine your .52 would fly it well, I just had the .72, and a little more ooomph off the water would be okay with me.

I also have a 1/5 Sig Cub built from a kit as an L-4 military version. The H-9 is only slightly smaller (Sig has a 84.5" wing), but the scale lines are almost identical. The instructions show the .50 mounted sideways, but I may mount my .72 inverted, due to the larger size and some engine mount considerations.

It's worth noting, the firewall and mount of the H-9 has no side or down thrust, but the horizontal stab has a notable positive incidence, where my Sig has downthrust in the firewall and a zero incidence H. stab.

The wing on the H-9 is supposed to build as a one-piece, with non-functional struts. I am looking at trying to build mine as a two piece wing, for convenience of transport. It has a big piece of spruce for a wing joiner, and it fits very snugly in both halves, so I may just glue it in one half, and keep the halves together with the wing bolts and locator pins in the forward part that fits to the front of the cabin.

Good luck on whatever you choose, hope this helps.