Neither. I would use a waterbased acrylic paint such as Sadolin Superdec. An interior deckhead does not need the properties offered by external enamels which are very difficult to apply to an overhead panel.
Just to cause havoc: I gave up using Toplac and now regularly (this week for example) use Epifanes Enamel. For me, it was much easier. Toplac I thought was rubbish. I will never use it again!
I have to say that I do feel Toplac is a superior paint (for topsides). It is hard to apply as it is so thick and needs careful conditioning (with Owatrol) and thinning (must use proprietary) and this requires some skill to get the levels right. The reason I think it is superior is durability. Rosie has managed 3 years over-coating intervals with Toplac and Epifanes does not even get close! With a higher oil content, Epifanes has a much glossier finish, and the Dutch know this aesthetic is a market winner!
I have given up using expensive marine paints below deck, and now use something like Sandtex 10 year exterior. It's not dirt cheap, but it's a lot cheaper than marine paint. It's easier to apply, seems to have a bit of flexibility so lasts well, and also seems more resistant to mould. Probably not as super glossy as either of your suggestions but if that's not the most important consideration, it's a lot more practical.
I have used Epifanes bootlack on topsides of our old gaffer & it was excellent. I have used Epifanes 2 pack & it was far superior to International.
Epifanes Monourethane was also good but if the conditions are not warm enough you will regret it! as it will take an age to go off & can wrinkle.
I just painted the Sabre with Toplac & did not find it thick at all, Rollered it on & tipped it off with a decent brush. I was pleased when someone asked "Who sprayed her?" So many variables but the most common one for poor results is trying to paint too early in the year when its chilly or damp. Pick the right conditions & you have a better chance.