newbie with a gsl-se

[FBob13]

i have an 85 gsl-se thats in great condition. i got it off of a guy who said he just replaced the engine, i did an atf treatment to be sure and replaced the spark plugs, wires and rotor cap. the car would continue to turn over and spudder but i couldnt get it to start up on its own. i checked for fuel delivery and spark and they came out good. it seems to me that the engine is flooding out. i dont have a compression tester though so i'm kinda of scared but i see no blue smoke out of the exhaust when its turning over. is there another series of diagnostics test help diagnose. i'm hoping its my injector seal rings and that would be a comparetively cheaper fix. but any input is greatly appreciated.

[FBob13]

a 1985 gsl se that i got a good deal on this last summer is about to be road worthy, when i purchased it the guy said that he just swapped the engines to one that was suppose to be good. but he had never gotten it to start. so i gave him $500 and went on my merry way with my new RX7, should be an easy fix hopefully, i started by changing out all the fluids to new fluids and checking my spark and fuel delivery were up to date with new filters and spark plugs. then i did a quick cleaning with dex/merc3. put in new spark plugs and wires and finally got her to fire up. she smoked for a little while then after warming up the exhaust cleared up to help me on concern with compression.
but theres one problem i have with my new RX7, it idles high, but my tach isnt functioning, and it makes this aweful clanking noise that gets louder as i rev the engine. i tried driving it around the parking lot and it has no power. idles high, revs slow, no power, continuing clanking noise that increases in volume with rpm increase.

i have checked all my fuses and changed them and put more gas in it. but i ran out of time at the shop. now it only starts with started fluid and a few cranks. i believe some of that is my battery though.