no experience with the DL103 on this arm, but why not stick with the original arm of your Thorens.
(TP13 or TP14)
It is not the best you can get, but IMO worth a try.
I did not try my DL on that arm, but if the arm has got no or very little play in it´s bearings, it should work well.
I don´t know the effective mass, but it is not a light arm.
When I got my TD150, an Ortofon MC20 was mounted.
It is lighter then the Denon, but has a slightly higher compliance.
With a tight budget, I´d go that way to see if this combination is satisfying me.
The DL103 has quite a stiff suspension and a tracking force of 2,5g , so the quality of the bearings is not that important.
(except of play!)
Low compliance carts don´t need sophisticated bearings with super low friction.
(high compliant carts do)
The TP13 misses the antiskating, but I don´t hear a difference with or without it on the Denon.
(I do slightly on the Shure)
Of course there might be an improvement with a better arm and antiskating, but that should be much less than on higher compliant carts.
I had the Denon on different heavy arms like an arm from a CEC BD2000, several other Japanese OEMs and my Polish Unitra.
The Denon almost sounded all the same with these arms.
My Shure V15III with Jico SAS- and original DN35- styli was very sensitive to more or less friction.
The masses of all these arms were around 12 to 16g without headshell and cart.
Denon and original Technics Headshell weigh around 15g.
So the effective mass was around 27 to 31g.
The arms sounding poor (mainly bass precision was missing) with the Shure,
did not audibly differ much (almost not) with the Denon.
By the way, doesn´t that old Thorens look cute with it´s original arm?
Just give it a try.
(if the original arm still exists and is ok)