The DC resistance of an AC transformer does not indicate what the transformer will draw when connected to AC. What matters is the impedance at the frequency of the AC. That impedance is much higher than 8 ohms, and is determined by the inductance of the windings as well as the load on the secondary, the losses in the core, and the DC resistance.
Ironically (bad pun intended), the primary of an ideal transformer would measure 0 ohms DC resistance and infinite AC impedance, when the secondaries are not connected to anything.
Now to the blown fuse.
If you feel lucky, and have lots of fuses, try using a higher-rated fuse (say 1 to 2 amps). Slow blow if you have it. Here's why:
The HV power supply in that tx uses silicon rectifiers and a capacitor filter. When you first turn on the power, there is an enormous surge as the supply tries to charge the filter capacitors. This surge dies down once they are charged - but it may be enough to blow a half-amp fast-blow fuse.
If that's not your style, or you don't have or don't want to risk fuses, or a bigger fuse still blows, here's the step-by-step:
1) Instead of replacing the fuse, wire an incandescent bulb across the fuse holder. For a transmitter of that size, anything from 40 to 100 watts should be OK. The idea is that if there's something drastically wrong, the lamp will light rather than blowing another fuse. Once the preliminary checks are done, the lamp is removed and the fuse replaced.
2) IIRC, that transformer has two secondaries: the HV secondary and the heater secondary.
The first test I would do to unsolder one of the HV secondary leads and one of the heater secondary leads, insulate them, power up and see what happens. If the series lamp lights dimly, or not at all, test for voltage at the heater secondary. If you get some voltage (may not be exactly 6.3 volts), you know the transformer is good and the primaries are phased correctly.
The correct phasing for 120 volt service is that the two "starts" are connected together, as are the two "finishes". Otherwise the two primaries oppose each others' inductance and the transformer draws enormous current.
3) If the above works out, power down, reconnect the heater secondary, and power up. The lamp should light dimly - if it lights brightly, there's a short in the heater wiring. Do this test first with the tubes removed, then, if it passes, replace them and see if they light.
4) If all the above works, reconnect the HV secondary and power up again. The lamp should brighten at first, then go dim.
73 de Jim, N2EY