You can obtain these thru DB editing in the data folder.
There are about 75+ ships, The strongest one is around number 60s which is union dreadnought. But since it is way too big for screen. You might wanted something smaller like those vic viper like capital instead which somewhere around number 40s or 50s. Just to note, 55s to 59 are useless drone and escort ships.
The ascended seraph is around before the 72 to after 76 which is the welsch (your own faction) ships set. The ascended death whatever giga ship is around 60s as well.
Note for ascended seraph ship, it does not come with its original equipment thru DB editing alone and since you can not refit it either then you have to set the gears as well thru DB edits which the weapon IDs are 1x 34, 2x 82, 3x 83 and 3x 84 then set an item 47 (or 40 what) with 4 quantities in there to match the original.
For side note, the missile and cannon of the Seraph are the strongest there in raw stats. But in actual usage, you may want to consider bringing the laser lance as well at least 1 or 2.
As for items, in 70s are the upgrade modules (except fews are around 30s) and the torpedoes ammo before the seraph set at 80s.
Of course you can set an item to bring to negative value and set the space-to-mass converter a lot to give you more mass or space allowance. Also give you more armors so you become invible (almost)