Snipe Police Ship (SNP 55 bpv): Don't get caught dead in this thing. Bad choice. It has pathetic weapons, and you don't even have the power to use them. No cloak either.

Snipe-A Frigate (SNA 65): From the SNP, the 2 ph-2 are upgraded to type-1 and you get a cloaking device. But you still have all the power problems. You do have great shields though, better than most cruisers.

KR F5 Frigate (K5R 78): This ship is much better than the Snipe series. Yes that's not saying much, but I mean it. It has a good power curve for an early era ship too, so you can run and charge your 2 Pl-F. Fly fast and stay far away, though, because your rear shields are really weak.

Battlehawk Destroyer (BH 85): The Battlehawk is probably the best Old-Series ship for its class. You do have the power to go decently fast, but I would still suggest the old-skool cloak tactics, because you aren't THAT quick, and the Pl-G's have FA arc only- not good for lobbing plasma while running.

Warbird cruiser (WB+ 60): Strange ship, and slow slow slow! You might see the 13 power and think that's not bad for a frigate. And then you notice the 1.00 move cost. Your best assets for this ship are its shields, cloak, and firepower. Charge while cloaked, and then pound them when you have your weapons charged. Make sure to use the pseudo wisely, and try the Anchor if you need to.

War Eagle Cruiser (WE 100): This has the same stuff as the Warbird, but with twice the engine power. But even with the better engines you can't fly around fast. It works best with the same tactics as the WB+.
Note: In the Middle era, the Romulans made a War Eagle refit, but I'm too lazy to add another ship. Basically, the WER (103 bpv) added 2 ph-3. It is one of the worst refits I've seen because the ph-3's point backwards, and if you're using cloak tactics with the WER, anything you'd need the ph-3's for (drone defense, etc) would need to be pointing forward.

KR D6 Cruiser (KR 115): Just like the K5R was a Rommie conversion of the Klink F5, this is a conversion of the D6. It is made for fast tactics, not cloaking tactics. This is because most Klingon-Romulan ships have more expensive cloaking costs, and they don't have the even-all-around shields. On the other hand, in the KR, you have the power to go speed 24 or whatever and arm plasmas. So go fast and dance your Plasma Ballet. It's a good match against a G-CA or F-CA, because even though it is a light cruiser, it's the fastest/biggest ship you have in this era.

Recommendations: For an Early-era Romulan battle, here are the best ships for their class and time (in my opinion):

Frigate- K5R

Destroyer- BH or WE (if the BPV is low enough).

Light Cruiser- KR

and so far you don't have any ships bigger than a light cruiser. So good luck :)