body ?

They didn't make a valiant signet in '70. The last year for it is '69. If it's a '69, the fenders will fit and look close. The main difference is the marker light on the '70 is slightly larger and it has a light in it, '69 are reflectors only, and of course, the emblem holes on the fenders are different. The grille is made from aluminum not plastic, the filler panel between the bumper and grille is the same, and so is the bumper and hood. There might be slight issues with grille mounting points on the fenders and hood latch brace, but it's nothing major.
I have a 2 '69 valiant projects and have used fenders from other years on them with no major problems other than the marker light holes and the emblem holes.
Everything would physically bolt up if you used the whole front clip.
I hope this helps.
Tom.