Hi,
IMHO, Swapping an aluminum Tekskid block the Cobra’s ran from 96’-99’ capable of near 1,000HP is insane to say the least, unless damaged beyond description .
The 4.6l blocks were square, stroke and bore were the same, the 5.4’s had 4.165” in. stroke & 4.6’s at 3.75”in. stroke. If you think that may be the case, locate BDC & pull a plug, insert a thin wooden dowel you marked it with the 4.6l’l stroke & the 5.4l’s stroke, yoiull see what the stroke iswhen you hit TDC whether 4.6 or 5.4.
Windsor Heads used (14) valves cover bolts, the Romeo used (11) bolts.
Providing a Romeo block was used with Romeo parts, many are interchangeable.
This may help...
Modular Motor engines for sale
fordcobraengines.com
It appears like a stock block minus the valve covers and the intake manifold difference, to name a couple..
Your best option is to decipher it is by the numbers stamped/cast onto the block.
Are you 100% it’s not a Cobra clone? Only mentioning it as many are manipulative as they’re worth more...
Best!
John